Pneumatic load balancing system and method

Abstract

According to the invention, a pneumatic load balancing system 1 is provided, which includes an actuating cylinder 14 for balancing a load 22. The system comprises a pressure sensor 21 for determining the pressure in the chamber 16 of the actuating cylinder, and a controller 5 for controlling the air pressure in the chamber of the actuating cylinder via at least one air supply valve 9, 10. The controller continuously or periodically obtains the current air pressure in the chamber from the pressure sensor during a load balancing sequence, when supplying air to the chamber via at least one air supply valve, and determines the balance air pressure in the chamber when the air pressure stops increasing or when the slope of the pressure increase falls below a predefined threshold, if air is supplied to the chamber, or when the air pressure starts to decrease, if air is released from the chamber. This determined balance air pressure is used as the balance air pressure of the system. Thereby, an automatic setting of the air pressure required for load balancing is achieved. The user does not need to manually supply the required air pressure, and the system will use the correct air pressure. Also, mistakes in setting the air pressure can be avoided.

Description

Technical Field

[0001] The present invention relates to a pneumatic system, related apparatus, and method for weight balance.

Background Art

[0002] Lifting operations in industry often require balancing the load being lifted. Conventional balancing devices, also called hoists, are generally characterized by a pressure-fluid actuated motor that includes a piston disposed within an expandable chamber and properly connected to a rotatable cable drum. A load attached to the hoist cable is raised, lowered, or held in a balanced state by controlling, with a controller, the pressure of the fluid introduced into the hoist chamber and acting on the piston. Such a hoist is operable to manually raise and lower a balanced load with minimal effort by adjusting the pressure of the fluid acting on the piston to a value sufficient to counteract the weight of the load. Thereby, a hoist operator can manipulate the load, including raising and lowering the load, with only a fraction of the force of the actual weight of the load.

[0003] An existing system for providing load / weight balance is US 3,758,079, which describes a control system for a fluid-actuated balance hoist that is operable to raise, lower, and automatically balance any weight load up to the maximum capacity of the hoist. The system includes a control circuit having a pressure regulating valve that senses the pressure within the hoist motor chamber necessary to balance the load and is operable to automatically adjust to maintain balance pressure values for various weight loads. The control circuit includes a pressure regulator that automatically senses the balance pressure and is operable to be positively locked at a balance pressure setpoint.

[0004] As another example, there is US 4,500,074, which also describes a system for load balancing.

[0005] There is always a need to improve load balancing systems in terms of accuracy, speed, and ease of use. Therefore, there is a need for improved load balancing systems and methods for controlling such systems. [Overview of the project]

[0006] The object of the present invention is to provide improved control and / or functionality for a pneumatic load balancing system.

[0007] This objective is achieved by the apparatus and method described in the attached claims.

[0008] The present invention provides a pneumatic load balancing system including an operating cylinder for balancing a load. The pneumatic load balancing system comprises a pressure sensor for determining the pressure in the chamber of the operating cylinder and a controller for controlling the air pressure in the chamber of the operating cylinder via at least one air supply valve. The controller is configured to continuously or periodically acquire the current air pressure in the chamber from the pressure sensor when supplying air to the chamber via the at least one air supply valve during a load balancing sequence, and to determine the balance air pressure in the chamber when, if air is supplied to the chamber, the air pressure stops rising or the pressure rise gradient falls below a predetermined threshold, or when, if air is released from the chamber, the air pressure begins to fall (or at a rate exceeding a certain threshold). The balance air pressure thus determined is then used as the balance air pressure for the operating cylinder of the pneumatic load balancing system. This achieves automatic setting of the air pressure required for load balancing. The user does not need to manually supply the required air pressure, and the system will use the correct air pressure. Furthermore, errors in setting the above air pressure can be avoided. The term "supply" may refer to both the supply of air to the chamber and the discharge of air from the chamber.

[0009] According to one embodiment, the pressure in the chamber is first set to an initial value before the current air pressure in the chamber is acquired continuously or periodically. In particular, the initial value may be set to the atmospheric pressure when air is supplied to the chamber, or to the system pressure (maximum system pressure) when air is released from the chamber. This provides a robust automatic setting sequence for the balanced air pressure.

[0010] According to one embodiment, the pneumatic load balancing system is configured to supply air to the chamber at a constant rate. This makes it easier and more accurate to determine when the rate of ascent stops or decreases.

[0011] According to one embodiment, a position sensor is provided to determine the position of the cylinder, and the controller is configured to determine the balance pressure using the output signal of the position sensor. By also using the position of the cylinder, a more accurate determination of the balance pressure can be achieved. Furthermore, anomalies in the balance pressure can be automatically detected.

[0012] According to one embodiment, the pneumatic load balancing system is configured to initiate the load balancing sequence based on a start signal. This allows the system to be set to trigger an automatic sequence for determining the balance pressure at any appropriate time. In particular, the start signal may be a user command signal.

[0013] According to another aspect of the present invention, a pneumatic load balancing system is provided, comprising an operating cylinder for balancing a load, the load being connected to the operating cylinder. The pneumatic load balancing system comprises a pressure sensor for determining the pressure in the chamber of the operating cylinder, and a controller for controlling the air pressure in the chamber of the operating cylinder via at least one air supply valve. The controller is configured to continuously or periodically acquire the current air pressure in the chamber from the pressure sensor and to determine a pressure drop to a pressure below the balance pressure. Based on the determined pressure drop, it can be determined that an accident event has occurred. This allows for taking appropriate action in the event of an accident, such as issuing a warning signal.

[0014] According to one embodiment, the operation of at least one air supply valve is monitored continuously or periodically, and the controller is configured to determine that an accident event has occurred based on the operation of the valve. This allows for more robust determination of accident events, as the operation of the valve can be used to provide additional information that helps determine the presence of an accident event.

[0015] According to one embodiment, the pneumatic load balancing system includes a position sensor that determines the position of the cylinder, and the controller is configured to use the output signal of the position sensor when an accident event occurs. This allows for more robust detection of accident events, as the position can be used to provide additional information that helps determine whether an accident event has occurred.

[0016] According to one embodiment, the accident event may be determined to be the load becoming detached from the operating cylinder.

[0017] According to one embodiment, the controller is configured to apply a predetermined setting to at least one air supply valve when an accident event is detected. This can prevent or at least reduce the negative consequences of the accident event. For example, the predetermined setting may include closing a valve used to increase the balance pressure. This prevents the pressure in the operating cylinder from rising and can prevent the operating cylinder from providing an increased force that could damage the surrounding load balance system. According to another embodiment, the predetermined setting may include opening a valve used to decrease the balance pressure.

[0018] According to one embodiment, the controller is configured to determine a pressure reduction to a pressure below the balance pressure when the pressure falls below a preset threshold. This provides a robust limit.

[0019] According to one embodiment, the controller is configured to apply predetermined settings based on a position obtained from a position sensor. When an accident event is detected, the controller is configured to store the position of the operating cylinder and subsequently control the position of the operating cylinder to the stored position. This ensures that when an accident event is detected, the pneumatic load balancing system endeavors to keep the operating cylinder in a stable position at the time the accident event was detected. This can reduce the risk of damage by preventing the operating cylinder from moving. The control can be performed in a closed loop.

[0020] According to one embodiment, when a position sensor for determining the position of the operating cylinder is provided, the controller uses the output from the position sensor to continuously or periodically acquire the position of the operating cylinder, and is configured to determine whether the operating cylinder is outside the allowable range. When it is determined that the operating cylinder is outside the allowable range, the controller is configured to drive the operating cylinder toward the allowable range. Thereby, further safety can be added to the pneumatic load balance system to prevent the pneumatic load balance system from operating the operating cylinder outside the safe range.

[0021] The present invention also extends to a method of operating a pneumatic load balance system according to the above.

Brief Description of Drawings

[0022] Hereinafter, the present invention will be described in more detail by way of example with reference to the accompanying drawings. In the drawings, [Figure 1] It is a diagram showing a load balance system. [Figure 2] It is a diagram showing a lift operation using a load balance system. [Figure 3] It is a diagram showing the pressure increase during air filling. [Figure 4] It is a flowchart showing the steps executed when setting the balance pressure. [Figure 5] It is a diagram explaining the operation of the balance pressure. [Figure 6] It is a diagram showing the pressure as a function of time while balancing and when the balanced weight drops. [Figure 7] It is a flowchart showing some steps executed when detecting an accident event. [Figure 8] It is a diagram showing various exemplary events when operating a pneumatic balance system. [Figure 9]A diagram showing various exemplary events when operating a pneumatic balance system. [Figure 10] A diagram showing various exemplary events when operating a pneumatic balance system. [Figure 11] A diagram showing various exemplary events when operating a pneumatic balance system.

Mode for Carrying Out the Invention

[0023] Hereinafter, the present invention will be more fully described with reference to the accompanying drawings showing specific embodiments of the present invention. However, the present invention can be embodied in many different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete and will fully convey the scope of the present invention to those skilled in the art. For example, similar or analogous components of different embodiments can be exchanged between different embodiments. Some components can be omitted from different embodiments. Like numbers refer to like elements throughout the specification.

[0024] FIG. 1 shows a pneumatically driven cylinder 14 controlled by a load balance system 1. The pneumatic cylinder 14 can be configured to operate as an actuator (operating cylinder) for lifting some weight 22. It is also envisioned that some load other than the weight 22 is coupled to the load balance system 1. Air is supplied to the load balance system 1 from an air supply unit 2, and the cylinder 14 is controlled by the load balance system 1. The following will be described in relation to the exemplary load balance system 1 of FIG. 1.

[0025] The pneumatic cylinder 14 includes a first chamber 15 having pressure A and a second chamber 16 having pressure B. The two chambers 15 and 16 are located on different sides of the cylinder 14 (typically on different sides of the cylinder head of the cylinder 14). In the exemplary embodiment of Figure 1, chamber 16 is pressurized and depressurized by an arrangement configuration including a pair of valves 9 and 10. The valves can be similar to those described, for example, in US10,641,397B2, but can be any type of valve suitable for use in a pneumatic load balancing system. Also, although valves 9 and 10 are shown as two valves in the exemplary embodiment of Figure 1, any number of valves are conceivable. Furthermore, for example, chamber 15 may be pressurized (and depressurized) by an arrangement configuration of auxiliary valves.

[0026] The operation of the cylinder is controlled by pressurizing (and depressurizing) the cylinder chamber 16. That is, air is supplied to the chamber 16 by supplying air to the chamber 16 or releasing air from the chamber 16. This provides a balancing force that can balance the weight of the weight 2 connected to the operating cylinder 14.

[0027] In the load balancing system shown in Figure 1, the force applied by the cylinder 14 is controlled by the controller 5. The controller controls the airflow rate via valves 9 and 10. Air is supplied to valves 9 and 10 via the air supply unit 2. The air supply unit 2 may be called the system air pressure and sets an upper limit on the maximum air pressure that can be reached in the chamber 16. By controlling the pressure in the cylinder chamber 16, the force applied to the weight 22 is controlled, and the weight of the weight 22 can be balanced. Typically, this control can be achieved by opening valve 9 and increasing the pressure in the chamber 16 by allowing air into the chamber 16. Similarly, valve 10 can be used to decrease the pressure in the chamber 16 by releasing air from the chamber 16.

[0028] The load balancing system 1 may, according to several embodiments, include a pressure sensor 21 that outputs the current pressure in the cylinder. In particular, the pressure in the pressurized / depressurized chamber 16 may be sensed by the pressure sensor 21. A position sensor 13 that outputs the current position of the cylinder 14 may also be provided. The output from the pressure sensor 21 and / or the output from the position sensor 13 may be supplied to the controller 5.

[0029] The controller 5 can also receive control input signals 8 from an external source, such as an operator operating the load balancing system. These control input signals could be, for example, signals to lift or lower the weight 22.

[0030] For example, assuming that the weight 22 is balanced by the pressure in the chamber 16, if a lift signal is received as the control input signal 8, the controller can activate valve 9 to increase the pressure in the chamber 16. This increases the force applied to the weight 22 by cylinder 14, causing the weight 22 to begin moving upward in the system shown in Figure 1. On the other hand, if a descent signal is received as the control input signal 8, the controller can activate valve 10 to decrease the pressure in the chamber 16. This reduces the force applied to the weight 22 by cylinder 14, causing the weight 22 to begin moving downward in the system shown in Figure 1.

[0031] The controller 5 can control the position of the actuating cylinder 14 in a closed loop using the position sensor 13. The desired position of the actuating cylinder 14 can then be stored by the controller 5. If the controller 5 determines that the current position from the position sensor 13 is outside the stored desired value (or outside the range around the stored desired value), it can actuate valve 9 or 10 to adjust the pressure B. Using this principle, the controller 5 can control the actuating cylinder 14 to maintain the stored position.

[0032] While balancing the weight 22, the pressure B in the cylinder 14 (i.e., the pressure in the chamber 16) is adjusted to correspond to the weight of the weight 22. At this time, pressure B exerts a force equal to the gravity of the weight 22. This pressure level of pressure B may be called the balance pressure. In practice, this can be obtained by storing the pressure required to balance the weight 22 in the controller 5. The controller 5 can compare the pressure required to balance the weight 22 with the pressure B obtained from the pressure sensor 21. If pressure B is lower than the pressure required to balance the weight 22, valve 9 is activated to increase the pressure. If pressure B is lower than the pressure required to balance the weight 22, valve 10 is activated to decrease the pressure.

[0033] Assuming that the weight 22 is balanced by the pressure B in the chamber 16, when an operator applies an upward force to the weight 22, the pressure in the chamber 16 decreases. This pressure drop in the chamber 16 is detected by the pressure sensor 21. The controller activates valve 9 to compensate for the pressure drop. The weight 22 moves upward. This function allows the operator to manipulate the weight 22 up and down using only a fraction of the force required to lift the weight 22.

[0034] Figure 2 shows a simple example of lift operation. First, at position a) in Figure 2, the lift device controlled by the pneumatic cylinder 14 is moved to the weight 22. The lift device is represented here by a hook connected to the actuating cylinder 14. Next, as shown in Figure 2b), the weight 22 to be moved is connected to the hook connected to the actuating cylinder 14. Then, balance pressure is supplied to the pneumatic actuating cylinder 14 so that the weight 22 is balanced. Then, as shown in Figure 2c), the weight 22 can be moved up and down in a simple manner by the operator.

[0035] However, for the operation shown in Figure 2 to function correctly, a balancing force corresponding to the weight of the weight 22 must be applied by the actuating cylinder 14. Therefore, the correct balancing force must be input to the balance system that controls the pneumatic cylinder 14. This force can be input, for example, as a certain weight by the operator. The system then converts that weight into pressure within the cylinder that provides the correct balancing force.

[0036] However, it would be beneficial if the balance system could automatically apply the correct balance force.

[0037] According to one embodiment, such automatic setting of the balancing force can be achieved by monitoring the pressure inside the cylinder chamber.

[0038] The flowchart sequence in Figure 4 illustrates how the balancing force is obtained by monitoring either pressure B or the position of actuator 14. Typically, the pressure in chamber 16 is set to an initial value before the weight is connected to the actuator. This initial value is typically very low, for example, zero or at least lower than the pressure corresponding to the minimum weight balanced by the working cylinder 14. In step 401, pressure B is set to this initial value and weight 22 is connected to actuator 14.

[0039] Next, pressure B is set to increase gradually in step 403. This increase may be performed at a certain set rate according to some embodiments. The gradual increase of pressure B at the set rate may be achieved by opening valve 9 to a constant flow velocity. This step may be initiated by an operator using an external signal 8 indicating that it is desired to lift weight 22.

[0040] Subsequently, in step 405, while the pressure is set to gradually increase at a set rate, the pressure is continuously or at least periodically monitored by the load balancing system 1 via the output from the pressure sensor 21.

[0041] In a typical scenario, the operating pressure, i.e., the air supply unit 2, can be set to 0.5 MPa. The weight of the weight 22 can correspond to a pressure of 0.2 MPa in the chamber 16. The rate of increase of pressure B can be set to 0 to 0.5 MPa / s. The rate of increase of pressure B is achieved by setting the flow rate of valve 9 to a constant flow velocity. As long as pressure B is lower than the pressure required to lift weight 22, the flow from valve 9 gives a gradual increase in pressure B, as shown in the diagram in Figure 3.

[0042] When the pressure inside chamber 16 reaches the pressure required to lift the weight 22, the weight 22 moves upward. As a result, the volume of chamber 16 expands, and the pressure gradient changes significantly. Figure 3 shows how the pressure gradient changes significantly when the pressure inside chamber 16 reaches the pressure required to lift the weight. Thus, when air is supplied to chamber 16 through the valve, the pressure increase stops, or at least the rate of increase decreases significantly.

[0043] In another embodiment, data from the position sensor 13 is used as a substitute for or supplement to data from the pressure sensor 21 in order to automatically determine the balance pressure required to obtain the balance force in the working cylinder 14. In such an embodiment, when the pressure in the chamber 16 reaches the pressure required to lift the weight 22 and the weight 22 moves upward, this movement can be detected by the position sensor 13. Once the lifting motion is detected, the pressure is recorded and used as the balance pressure.

[0044] In step 405, the controller 5 detects a (significant) change in the pressure increase rate from the pressure sensor 21 and / or a movement from the output of the position sensor 13. When such a change in the pressure increase rate and / or a change in position is detected, pressure B is recorded in step 407 and used as the pressure to balance the weight 22. The operator can then start using the load balancing system 1, as with existing systems, and start moving the weight using the balance pressure thus set. This achieves automatic balance pressure setting.

[0045] In another embodiment, the sequence for determining the balance pressure is started at a certain high pressure, followed by the release of air from the chamber 16. In such a scenario, the weight 22 is lifted by the high pressure, and as the air is released from the chamber 16, the balance pressure is reached, at which point the pressure in the chamber begins to decrease at a considerable rate above a certain threshold. This sequence can be captured by recording the position from the position sensor 13 as described above. The initial pressure used when starting from a high pressure may be, for example, the air supply pressure 2 (system pressure), or another high pressure above a preset value that ensures the pressure in the chamber is equal to or greater than the balance pressure when the sequence for determining the balance pressure starts.

[0046] Once the weight 22 is balanced and the operator begins to move the weight, there is a risk of an accident occurring if the weight 22 is accidentally dropped and the operating cylinder is not stopped. To address such an emergency, the load balancing system 1 described herein may be configured, according to several embodiments, to continuously or periodically record the pressure in the cylinder 14 and / or the position of the cylinder 14 using data from the pressure sensor 21 and / or the position sensor 13, respectively.

[0047] For example, an accident could occur if weight 22 falls. The weight no longer pulls against pressure B in chamber 16. The arm of actuator 14 moves upward, and chamber 16 expands. This reduces the pressure. While balancing, the pressure reduction works in the opposite direction. This causes more fluid to flow into chamber 16. The arm of actuator 14 moves upward, and this could cause an accident. This is an example of an accident that can occur when using the balance system 1.

[0048] As described above, the controller 5 may be configured to record the pressure B in the chamber 16. Typically, pressure B is adjusted to a balance pressure by the controller 5. An operator can apply force to the weight 22, which results in a deviation of pressure B from the balance pressure. This deviation is reversed by the controller 5. As a result, the weight 22 moves in the direction of the force applied by the operator. The force applied by the operator is much less than the force required to lift the weight 22. Therefore, the deviation of pressure B from the balance pressure is much smaller than the balance pressure. Figure 5 shows how the settings of valves 9 and 10 can be used to control the balance pressure B. Thus, opening valve 9 acts to increase pressure B, and opening valve 10 acts to decrease pressure B.

[0049] Figure 6 shows the pressure B as a function of time when the weight 22 is balanced. In this example, the weight 22 is successfully balanced between time 0 and time T1. At time T1, the weight 22 is dropped. The x-axis represents time, and the y-axis represents pressure B. The line shows the balancing pressure of the weight 22. Between time 0 and time T1, the weight 22 is balanced at pressure B.

[0050] Between time 0 and time T1, pressure B is controlled to the balance pressure. Pressure B is monitored by controller 5 using a signal from pressure sensor 21. If pressure B is lower than the balance pressure, valve 9 is activated by controller 5 to increase pressure B. If pressure B is higher than the balance pressure, valve 10 is activated by controller 5 to decrease pressure B.

[0051] Typically, if no external force is applied to the weight 22, pressure B will be stable. In this case, the difference between pressure B and the balance pressure will be very small. In this case, the values ​​recorded in the controller 5 will indicate that the valve is not operating, that there is no change in pressure B, and that there is no change in the position of the actuator 14.

[0052] The operator can apply an upward force to the weight 22, resulting in a decrease in pressure B. This decrease in pressure B will be detected by the controller 5. The controller 5 will then activate the valve 9, resulting in an increase in pressure B. The position of the actuator 14 can be monitored by the position sensor 13, and an upward change in position will be detected. In this case, the values ​​recorded by the controller 5 will indicate that the valve 9 is activated, there is a positive pressure gradient in pressure B, and an upward change in the position of the actuator 14.

[0053] The operator can apply a downward force to the weight 22, resulting in an increase in pressure B. This increase in pressure B will be detected by the controller 5. The controller 5 will then activate the valve 10, resulting in a decrease in pressure B. The position of the actuator 14 may be monitored by the position sensor 13, and a downward change in position will be detected. In this case, the values ​​recorded by the controller 5 will indicate that the valve 10 is activated, there is a negative pressure gradient in pressure B, and a downward change in the position of the actuator 14.

[0054] At time T1, weight 22 falls. The load of weight 22 no longer pulls actuator 14 downward, causing a rapid upward movement of actuator 14. This will result in a decrease in pressure B. As a result, weight 22 no longer compresses chamber 16, and since the pressure does not rise, valve 9 will act. In this case, the values ​​recorded in controller 5 will show a considerably higher decrease in pressure B than in typical conditions, valve 9 acting, a negative pressure gradient of pressure B, and an upward position change of actuator 14.

[0055] To detect whether the weight has fallen, a detection limit may be set as shown in Figure 6. The actuator (cylinder 14) may be selected so that the balance pressure of the weight 22 is, for example, 0.2 MPa. Typically, the deviation of pressure B from the balance pressure is less than 0.0005 MPa. A detection limit higher than the normal deviation from the balance pressure is set. In this example, the detection limit may be set to 0.005 MPa.

[0056] According to several embodiments, the controller 5 can detect a negative pressure gradient of pressure B, which is linked to the operation of the valve 9, in order to detect whether the weight 22 has fallen. This provides a more robust detection mechanism.

[0057] According to several embodiments, the controller 5 can detect a pressure B lower than the balance pressure, which is associated with an upward position change. This results in a more robust detection mechanism.

[0058] Once the controller 5 detects an accident event, for example, caused by the actuator dropping the weight 22, this information can be used to restrict the movement of the system in order to prevent further dangerous events. For example, the load balancing system can be controlled to prevent the actuator piston from moving. This can be done by deactivating (closing) valves 9 and / or 10. This cuts off the air in the chamber 16, thus preventing the cylinder from moving. According to another embodiment, the controller 5 can prevent the movement of the actuator piston by deactivating valve 9 and activating valve 10. This reduces the pressure B and prevents the actuator 14 from moving upward. In this way, accidents can be avoided or limited by controlling valves 9 and 10 to predetermined settings in response to detected accident events.

[0059] Figure 7 shows a flowchart illustrating the steps performed when detecting an accident event. First, in step 701, the system continuously or periodically acquires the current air pressure in the chamber from a pressure sensor. Next, in step 703, a pressure drop to below the balance pressure is determined. In step 703, if a pressure drop to below the balance pressure is determined, for example, if the pressure falls below a predetermined threshold, a pressure drop may be determined. This ensures that noise or normal system operation does not trigger the determination that a pressure drop has occurred. In step 705, the system determines that an accident event has occurred based on the determined pressure drop. In addition to determining that an accident event has occurred based on a pressure drop, the system may also determine that an accident event has occurred based on valve operation and / or position signals, according to some embodiments. More detailed examples showing how such signals may be used are illustrated and described below in conjunction with Figures 8 to 11. In response to the determination of an accident event, the controller may be configured in step 707 to apply a predetermined setting to at least one air supply valve.

[0060] A further cause of accidents is when the weight 22 moves outside a safe range, either upward or downward. For example, this can occur if there is an obstacle in the path of the weight 22. If the weight 22 hits the obstacle, it may damage the obstacle or the weight 22, or cause other accidents. To prevent this, the controller 5 may be configured to allow movement of the weight 22 within a certain range. In this case, the controller 5 is configured to monitor the position of the actuator using the position sensor 13.

[0061] If the position of the actuator cylinder 14 moves above (outside) the allowable range, the controller 5 detects this using the position sensor 13. The cylinder 14 is then forcibly returned to the allowable range. For example, valve 9 is closed and valve 10 is opened, which reduces the pressure in the chamber 16. As a result, the weight 22 moves downward and returns to the allowable range if it is above the maximum allowable height. In another scenario, if the position of the actuator cylinder 14 moves below the allowable range, the controller 5 detects this using the position sensor 13. Valve 9 is then opened and valve 10 is closed, which increases the pressure in the chamber 16. As a result, the weight 22 moves upward and returns to the allowable range.

[0062] According to several embodiments, the controller 5 may be configured to detect a negative pressure gradient of pressure B, along with other input signals such as valve operation and / or position signals, in order to detect an accident event, such as when the weight 22 falls. Figures 8, 9, 10, and 11 show different examples of the operation of a balance actuator having a weight 22 attached to the actuator 14.

[0063] Figure 8 shows an example where the weight 22 is balanced with the pressure B inside the chamber 16. No external force is applied to the weight 22. As a result, the pressure remains constant, valves 9 and 10 remain deactivated (closed), and the position sensor 13 measures a constant position.

[0064] Figure 9 shows an example where an upward force is applied to the weight 22 by the operator at time 0. Initially, the pressure B decreases as the external force expands the chamber 16. At time T1, the decrease in pressure B is detected by the controller 5, and valve 9 is activated to counteract the decrease in pressure B. Between time T1 and time T2, the controller detects an increase in pressure B as a result of valve 9's operation. If position sensor 13 is connected to controller 5, upward movement is also detected. Figure 10 shows the case where a downward force is applied to the weight 22 by the operator at time 0. Here, the pressure B increases as the chamber 16 is compressed by the external force. At time T1, the increase in pressure B is detected by controller 5, and valve 10 is activated to counteract the increase in pressure. Between time T1 and time T2, the controller detects a decrease in pressure B as a result of valve 10's operation. If position sensor 13 is connected to controller 5, downward movement is also detected.

[0065] Figure 11 shows an example where the load 22 is dropped at time 0. As a result, pressure B decreases as described above. This decrease is detected by the controller 5 at time T1, and valve 9 is activated to counteract the decrease in pressure B. Since the weight 22 is detached from actuator 14, the chamber 16 expands further instead of the pressure B increasing. After time T1, the controller detects the decrease in pressure B as a result of valve 9's activation. If position sensor 13 is connected to controller 5, upward movement is also detected.

[0066] In the example shown in Figure 11, a decrease in pressure is detected as a result of the operation of valve 9. This is in contrast to the examples shown in Figures 9 and 10, where the operation of valve 9 increases pressure B, and the operation of valve 10 decreases pressure B. Therefore, the operation of valve 9 can be used to improve the determination of accident events such as the dropping of a weight.

[0067] Furthermore, in the example shown in Figure 11, upward movement is detected by the position sensor 13 in combination with pressure B lower than the balance pressure. This is in contrast to the examples in Figures 9 and 10, where pressure B higher than the balance pressure gives upward movement, and pressure B lower than the balance pressure gives downward movement. Therefore, readings from the position sensor can be used to improve the determination of accident events such as the dropping of a weight.

[0068] Furthermore, Figure 6 shows the threshold for pressure B. When the pressure falls below the threshold, a detached load is detected. The threshold is typically chosen so that noise or normal system operation does not trigger a determination that the pressure has decreased. A further advantage of linking the negative gradient of pressure B to the operation of valve 9 is that the controller 5 can detect the dropped weight before the pressure falls below the threshold in Figure 6. Therefore, if the valve signal is used together with the pressure signal to determine alarm events such as a dropped weight, the system can be made to react more quickly to such accidents. Similarly, by linking upward movement to pressure B below the balance pressure, the controller 5 can be made to detect the drop of weight 22 before the pressure falls below the threshold in Figure 6.

Claims

1. A pneumatic load balancing system (1), An operating cylinder (14) for balancing the load (22), A pressure sensor (21) for determining the pressure inside the chamber (16) of the above-mentioned operating cylinder, A controller (5) for controlling the air pressure in the chamber of the operating cylinder via at least one air supply valve (9, 10) and Equipped with, The above controller, during the load balancing sequence, - When supplying air to the chamber via at least one of the above air supply valves (9, 10), the current air pressure in the chamber is obtained continuously or periodically from the pressure sensor. - When air is supplied to the chamber, the balance air pressure in the chamber is determined when the air pressure stops rising or when the pressure rise gradient falls below a predetermined threshold, or when air is released from the chamber, when the air pressure begins to decrease. - Set the above balance air pressure to the balance air pressure determined above. A pneumatic load balancing system characterized by being configured in such a way.

2. In the pneumatic load balancing system according to claim 1, The pressure within the chamber is first set to an initial value before the current air pressure within the chamber begins to be acquired continuously or periodically. A pneumatic load balancing system characterized by the following features.

3. In the pneumatic load balancing system described in claim 2, The above initial value is set to atmospheric pressure. A pneumatic load balancing system characterized by the following features.

4. In the pneumatic load balancing system according to any one of claims 1 to 3, The above-described pneumatic load balancing system is configured to supply air to the chamber at a constant speed. A pneumatic load balancing system characterized by the following features.

5. In the pneumatic load balancing system according to any one of claims 1 to 4, The system includes a position sensor (13) that determines the position of the cylinder, The controller described above is configured to determine the balance pressure using the output signal from the position sensor. A pneumatic load balancing system characterized by the following features.

6. In the pneumatic load balancing system according to any one of claims 1 to 5, The above-described pneumatic load balancing system is configured to start the load balancing sequence based on a start signal (8). A pneumatic load balancing system characterized by the following features.

7. In the pneumatic load balancing system according to claim 6, The above start signal is a user command signal. A pneumatic load balancing system characterized by the following features.

8. A method for a pneumatic load balancing system according to claim 1, The above system is An operating cylinder (14) for balancing the load (22), A pressure sensor (21) for determining the pressure inside the chamber (16) of the above-mentioned operating cylinder, A controller (5) for controlling the air pressure in the chamber of the operating cylinder via at least one air supply valve (9, 10) and Equipped with, The above method, - When supplying air to the chamber via at least one of the above air supply valves (9, 10), the current air pressure in the chamber is obtained continuously or periodically from the pressure sensor. - When air is supplied to the chamber, the balance air pressure in the chamber is determined when the air pressure stops rising or when the pressure rise gradient falls below a predetermined threshold, or when air is released from the chamber, when the air pressure begins to decrease. - Set the above balance air pressure to the balance air pressure determined above. This includes A method characterized by the following:

9. In the method described in claim 8, The pressure within the chamber is first set to an initial value before the current air pressure within the chamber begins to be acquired continuously or periodically. A method characterized by the following:

10. In the method according to claim 9, The above initial value is set to atmospheric pressure. A method characterized by the following:

11. A pneumatic load balancing system (1), It is equipped with an operating cylinder (14) for balancing a load (22), and the load is connected to the operating cylinder. The above system (1) comprises a pressure sensor (21) for determining the balance pressure and the pressure inside the chamber (16) of the operating cylinder, and a controller (5) for controlling the air pressure inside the chamber of the operating cylinder via at least one air supply valve (9, 10). The above controller is - The current air pressure in the chamber is acquired continuously or periodically from the pressure sensor mentioned above. - Determine the pressure reduction to a pressure below the above balance pressure, - Based on the pressure reduction determined above, it is determined that an accident event has occurred. A pneumatic load balancing system characterized by being configured in such a way.

12. In the pneumatic load balancing system according to claim 11, The operation of at least one of the above air supply valves (9, 10) is monitored continuously or periodically. The controller determines that a fault event has occurred based on the pressure drop and valve operation determined above. A pneumatic load balancing system characterized by the following features.

13. In the pneumatic load balancing system according to claim 11 or 12, The system includes a position sensor (13) that determines the position of the cylinder, The above controller is configured to use the output signal from the above position sensor when an accident event occurs. A pneumatic load balancing system characterized by the following features.

14. In the pneumatic load balancing system according to any one of claims 11 to 13, The above accident event is determined to be the above load detaching from the above operating cylinder. A pneumatic load balancing system characterized by the following features.

15. In the pneumatic load balancing system according to any one of claims 11 to 14, The above controller is configured to apply predetermined settings to at least one air supply valve when an accident event is detected. A pneumatic load balancing system characterized by the following features.

16. In the pneumatic load balancing system according to claim 15, The above predetermined setting includes closing the valve used to increase the balance pressure. A pneumatic load balancing system characterized by the following features.

17. In the pneumatic load balancing system according to claim 15 or 16, The above predetermined settings include opening the valve used to reduce the balance pressure. A pneumatic load balancing system characterized by the following features.

18. In the pneumatic load balancing system according to any one of claims 11 to 17, The above controller is configured to determine a pressure reduction to a pressure below the balance pressure when the above pressure falls below a preset threshold. A pneumatic load balancing system characterized by the following features.

19. In the pneumatic load balancing system according to any one of claims 11 to 18, When the above controller is configured to apply predetermined settings based on the position obtained from the position sensor, The above controller is - When the above accident event is detected, the above position of the operating cylinder is stored, - Control the position of the above operating cylinder to the above stored position. It is configured in such a way A pneumatic load balancing system characterized by the following features.

20. In the pneumatic load balancing system according to any one of claims 11 to 19, When a position sensor is provided for determining the position of the above-mentioned operating cylinder, The above controller is - Using the output from the above position sensor, the above position of the above operating cylinder is acquired continuously or periodically. - Determine whether the above operating cylinder is outside the permissible range. - When it is determined that the above operating cylinder is outside the allowable range, the operating cylinder is driven towards the allowable range. It is configured in such a way A pneumatic load balancing system characterized by the following features.

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