JP2022098283A - Fluid pressure linear motion actuator, composite actuator, and control method for composite actuator - Google Patents

Abstract

To provide a fluid pressure linear motion actuator that can detect a lateral load applied to a piston rod to improve work efficiency for installation of a cylinder and monitor a state of, for example, wear of a bearing during operation.SOLUTION: A plurality of force sensors 80 is built in a circumferential direction between a rod bush 40 of a bearing part 55 of a fluid pressure linear motion actuator 200 and a retainer 50, and based on the force detected by the force sensors 80, the magnitude and direction of a lateral load applied to the bearing part 55 are output.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fluid pressure linear actuator capable of detecting a lateral load, a composite actuator, and a control method for the composite actuator.

The following inventions are disclosed in relation to the lateral load on the linear actuator.

Patent Document 1 (Japanese Unexamined Patent Publication No. 2019-116927) discloses a wear detection method and a system for linear actuators such as pneumatic cylinders, hydraulic cylinders, and electric cylinders.

In Patent Document 1, a physical quantity detection sensor is attached to a linear acting actuator that pushes and pulls a pressurized object while a pushing and pulling member connected to the rod applies a lateral load different from the linear moving direction, and pushes and pulls the pressurized object. The external force generated between the mounting member and the tube is detected by the physical quantity detection sensor, and is compared with the standard external force data detected in the state where there is no abnormality stored in the calculation storage judgment processing device. It is determined whether it is in an abnormal state or not.

Patent Document 2 (Japanese Unexamined Patent Publication No. 05-332323) discloses a composite actuator having good straightness of a piston rod.

In Patent Document 2, a table is attached to the tip of a piston rod of a linear actuator so that it can reciprocate and rotate integrally with the rod, and a bearing housing is attached to the table so that the piston rod can reciprocate and rotate relative to the table. By providing the bearing housing with a guide rod parallel to the piston rod and guided by a guide hole provided in the rod cover of the linear actuator and the body of the swing actuator, the reciprocating movement of the piston rod is parallel to the guide rod. The guide is made to improve the straightness.

Further, regarding the configuration including a plurality of linear acting actuators arranged in parallel and pushing and pulling one pressurized object, the following Patent Document 3 (Japanese Patent Laid-Open No. 2005-189875) and Patent Document 4 (Japanese Patent Laid-Open No. 5) -11156A) is disclosed.

In Patent Document 3, a table that freely moves relative to a support table on the same plane, a support table that supports the table facing the table, and a table that freely moves relative to the support table on the same plane. A plurality of table motion means, each of which is mounted on the upper surface of the support table and rotatably supports one end side of the table motion means, and a lower surface of the table. A second rotation support member that is mounted on the table and rotatably supports the other end side of the table moving means, and is located between the first rotation support member and the second rotation support member to drive the table. A free-moving mechanism of the table, characterized in that it is equipped with a driving means, is described.

Further, in Patent Document 4, a table that freely moves relative to the support table on the same plane, a support table that supports the table facing the table, and a table that is relatively free to move the table on the same plane with the support table. A first rotary support member, which comprises a plurality of table motion means for exercising, and each of the plurality of table motion means is mounted on the upper surface of a support table and rotatably supports one end side of the table motion means. A second rotation support member mounted on the lower surface of the table and rotatably supporting the other end side of the table moving means, and a table between the first rotation support member and the second rotation support member. A free-moving mechanism of a table is described, characterized in that it comprises a driving means for driving.

Japanese Unexamined Patent Publication No. 2019-116927 Japanese Unexamined Patent Publication No. 05-332323 Japanese Unexamined Patent Publication No. 2005-189075 Japanese Unexamined Patent Publication No. 5-11156

In the linear actuator, the piston rod housed in the cylinder tube is supported by a bearing portion composed of a cylindrical rod bush and a retainer covering the outer circumference of the rod bush. The retainer is fixed to the cylinder tube with a tie rod and a hexagon nut. In this case, the rod bush must be fixed parallel to the piston rod. This is because if the rod bush is not parallel to the piston rod, a load is applied to a part of the rod packing in the circumferential direction, and deterioration such as wear of the rod packing progresses. In the installation work of the linear actuator, centering (shaft alignment) between the piston rod and the bearing portion is performed for this purpose. However, in the cylinder installation work, it is difficult to adjust the parallelism between the rod bush and the piston rod with high accuracy, and the work efficiency is poor.
Even when the parallelism between the rod bush and the piston rod is adjusted with high accuracy, if a load in the direction perpendicular to the axial direction of the piston rod is applied to the tip of the piston rod, the rod packing of the bearing portion A load is applied to a part of the circumferential direction, and deterioration such as wear of the rod packing progresses.
In order to prevent deterioration due to wear of the rod packing of the bearing portion of these linear actuators, it is necessary to detect the lateral load applied to the piston rod.

Further, in the composite actuator in which a plurality of linear acting actuators are arranged in parallel and one pressurized object is pushed and pulled in cooperation with each other, the balance of the force of each of the plurality of linear acting actuators pushing and pulling the pressurized object is balanced. If it collapses, a lateral load is also applied to the piston rod, causing wear and deterioration of the bearing.

In the wear detection method and system of the linear actuator described in Patent Document 1, in the linear actuator that operates while applying a lateral load, the axial force applied to the piston rod is detected, and the axial force is applied from the normal state. By detecting the change, the lateral load is indirectly detected, and the wear of the linear actuator is detected.
In this case, not only can it not be used to improve the efficiency of cylinder installation work, but also in the wear detection of the linear motion actuator, a specific "push-pull member connected to the rod applies a lateral load different from the linear motion direction. However, it can be used only for "a linear actuator that pushes and pulls a pressurized object", and it cannot detect a lateral load in a wide range of applications.

The composite actuator with a guide rod described in Patent Document 2 does not detect the lateral load of the piston rod, but by providing a guide rod parallel to the piston rod and guided to the guide hole of the rod cover of the linear acting actuator. , Is an invention to reduce the lateral load of the piston rod.
In this case as well, not only can it not be used to improve the efficiency of cylinder installation work, but it cannot be applied to a normal linear actuator without a guide rod.

In the free motion mechanism of the table described in Patent Document 3, two table motion mechanisms are arranged substantially in parallel and drive the table in cooperation with each other. The two table motion mechanisms described in Patent Document 3 control the displacement amount by giving a command value to the motor by the built-in clock of the dedicated controller, and accurately control the displacement amount of the two table motion mechanisms. Can be done. On the other hand, in the case of a hydraulic actuator, it is difficult to control the displacement amount, so that it cannot be used as it is for the free motion mechanism of the table described in Patent Document 3.

In the stage device described in Patent Document 4, a piezo actuator as two parallel linear acting actuators and a counter spring for giving a preload to the piezo actuator are arranged to move the Y stage in cooperation with each other. It is well known that in a general piezo element, even if the same voltage or the same charge is applied, the displacement differs depending on the load. However, the piezo actuator described in Patent Document 4 is a feedback element (in-self). For example, a strain gauge) having a self-contained displacement amount is used. That is, also in the case of Patent Document 4, the displacement amount can be accurately controlled as a piezo actuator. On the other hand, in the case of a hydraulic actuator, it is difficult to control the displacement amount, so that it cannot be used as it is for the stage device of the table described in Patent Document 4.

A main object of the present invention is to improve the work efficiency of cylinder installation by incorporating a sensor in the bearing of a fluid pressure linear actuator and detecting the lateral load applied to the piston rod, and to improve the work efficiency of the cylinder installation and to wear the bearing during operation. It is an object of the present invention to provide a fluid pressure direct acting actuator capable of monitoring such a state and preventing the occurrence of a defect such as a leak in advance.
A second object of the present invention is the lateral load of each fluid pressure direct acting actuator in a composite actuator in which a plurality of fluid pressure direct acting actuators are arranged in parallel with each other and push and pull one pressurized object in cooperation with each other. It is an object of the present invention to provide a composite actuator capable of controlling the operating amount of each actuator so as to reduce the pressure, and a method for controlling the composite actuator.

(1)
The fluid pressure linear actuator according to one aspect has a plurality of force sensors built in the bearing portion in the circumferential direction, and outputs the magnitude and direction of the lateral load applied to the bearing portion.

The piston rod is fixed to the piston in the cylinder and slidably fixed by the bearing portion. When a lateral load is applied to the piston rod, the piston rod pushes the bearing portion in the direction in which the lateral load is applied. Therefore, if multiple force sensors are built in the bearing in the circumferential direction, the magnitude and direction of the lateral load applied to the bearing can be detected by investigating which force sensor receives how much force. Can be done.
As a result, the load and direction applied laterally to the piston rod can be known numerically, so that the cylinder installation work, which has relied on the experience of the operator so far, can be performed efficiently and reliably. Furthermore, when the shaft is tilted due to long-term use of the piston, a load is applied to the bearing part and wear progresses, causing a problem that the fluid inside the piston leaks. Therefore, it is possible to prevent the occurrence of defects in advance.

(2)
The fluid pressure linear motion actuator according to the second invention is a fluid pressure linear motion actuator according to one aspect, and the bearing portion is composed of a tubular rod bush and a retainer or a mounting flange that covers the outer periphery of the rod bush. The sensor is a strain gauge and may be disposed between the rod bush and the retainer or mounting flange.
Some fluid pressure direct acting actuators have a mounting bracket that fixes the retainer on the outside of the retainer, and some have a mounting flange that integrates the retainer and the mounting bracket that directly covers the outer circumference of the rod bush. .. In the case of a linear actuator in which the mounting flange directly covers the outer circumference of the rod bush, the force sensor is disposed between the rod bush and the mounting flange.

In the bearing portion, the piston rod is slidably fixed to the cylindrical rod bush, and the retainer covers the outer circumference of the rod bush. Since the lateral load applied from the piston rod to the rod bush is transmitted from the rod bush to the retainer, by disposing a strain gauge between the rod bush and the retainer, the strain disposed in the direction in which the lateral load is applied. The gauge can detect the magnitude of the lateral load applied to the bearing.

(3)
The fluid pressure linear motion actuator according to the third invention is the fluid pressure linear motion actuator according to the second aspect from the first aspect, and has three or four force sensors in the circumferential direction of the bearing portion. The magnitude and direction of the lateral load applied to the bearings, which are arranged at equal intervals, may be calculated based on the force detected by two of the plurality of force sensors.

When there are three force sensors, the angle between the two adjacent force sensors and the axis of the rod bush is set to 120 degrees, and when there are four force sensors, the two adjacent force sensors are set. It is desirable to set the angle between the force sensor and the axis of the rod bush to 90 degrees. In both cases, the lateral load is detected by the two force sensors. The magnitude and direction of the lateral load can be calculated from the magnitude of the force detected by each force sensor.

(4)
The fluid pressure linear actuator according to the fourth aspect of the invention further comprises a display device in the fluid pressure linear actuator according to the third invention, and the display device includes the specifications of the piston rod and the force sensor. By inputting, the load value and direction of the lateral load may be displayed and / or output to the outside.

In this case, the outputs of the two force sensors are converted into load values by referring to the sensitivity of the sensors, and the load values and directions of the lateral load are calculated and displayed based on these load values, and / or. It may be output to the outside. In addition, using the ratio of the distance from the tip of the piston rod to the piston and the distance from the bearing to the piston, the load value when a lateral load is applied to the tip of the piston rod is displayed and / or. It may be output to the outside.

(5)
The fluid pressure linear actuator according to the fifth invention is the fluid pressure linear actuator according to the fourth invention, when the display device constantly monitors the load value of the lateral load and detects a load value outside the appropriate range. An alarm signal may be output and / or a stop signal may be output to the drive device of the fluid pressure linear actuator.

When a lateral load outside the proper range is applied, the operation of the fluid pressure linear actuator can be stopped by notifying the operator with an alarm signal and outputting a stop signal to the drive device of the fluid pressure linear actuator. ..

(6)
The fluid pressure linear actuator according to the sixth invention is the fluid pressure linear actuator according to the fourth to fifth inventions. The display device constantly monitors the direction of the lateral load, and the lateral load in the direction outside the appropriate range is applied. An alarm signal may be output when it is detected.

Even in applications where a lateral load is constantly applied to the piston rod, if a lateral load is applied in a direction outside the appropriate range, the operator can be notified by an alarm signal.

(7)
The compound actuators according to the other aspects are arranged in parallel with each other and control a plurality of actuators that push and pull one pressurized object in cooperation with each other, a drive device for driving each of the plurality of actuators, and a drive device. The plurality of actuators include a control device, and the plurality of actuators include the fluid pressure direct acting actuator according to the third aspect of the invention, and the fluid pressure direct acting actuator outputs the magnitude and direction of the lateral load to the control device for control. The device controls the drive device so that the magnitude of the lateral load of the fluid pressure linear actuator is small.
That is, at least one of the plurality of fluid pressure direct acting actuators is the fluid pressure direct acting actuator according to the third aspect of the present invention, and outputs the magnitude and direction of the lateral load to the control device and controls the control device. Controls the drive so that the magnitude of the lateral load of the plurality of fluid pressure linear actuators is small.

In a composite actuator that pressurizes one object to be pressurized using multiple fluid pressure direct acting actuators, it is difficult to confirm whether or not the operating amounts of the respective fluid pressure direct acting actuators are completely the same. Actually, the operating amount may differ for each actuator. As described above, when the operating amount of each actuator is different, the composite actuator is distorted inside the device, which causes a failure such as breakage of parts due to metal fatigue.
In this case, a lateral load is generated on each piston rod. For example, when pushing one object to be pressed by two fluid pressure linear actuators arranged in parallel and symmetrically, if the amount of operation of the fluid pressure linear actuator on the right side is large, a lateral load in the left direction is applied to the piston rod. Is applied. If at least one of the plurality of fluid pressure direct acting actuators is the fluid pressure direct acting actuator according to the third aspect from one aspect, the lateral load in the left direction can be detected, so that the lateral load in the left direction can be detected. The driving force of the left and right actuators can be controlled so that the load becomes small.
As a result, the operating amount of each actuator can be made uniform, so that the force of each actuator can be reliably and efficiently transmitted to the object to be pressurized, and the failure of the composite actuator can be prevented.
As the drive device for driving the plurality of fluid pressure direct acting actuators, a drive device (pump) may be connected to each actuator, or a switching valve or a servo valve between each actuator and one pump, respectively. It may be configured by inserting.

(8)
The control method of the composite actuator according to still another aspect is to drive a plurality of actuators, which are arranged in parallel with each other and push and pull one pressurized object in cooperation with each other, and a drive device for driving each of the plurality of actuators. A method of controlling a composite actuator including a control device for controlling a device, in which at least one of a plurality of actuators is a fluid pressure direct acting actuator, and the fluid pressure direct acting actuator detects the magnitude and direction of a lateral load. , A step of inputting to the control device (input step) and a step of controlling the driving force of the driving device with respect to each of the plurality of actuators so that the control device reduces the magnitude of the lateral load (control step). include.

When pushing and pulling one pressurized object in cooperation with multiple fluid pressure linear actuators arranged in parallel with each other, if the displacement amounts of the plurality of fluid pressure linear actuators are different, a lateral load is generated on the piston rod. do. In this case, the lateral load can be reduced by detecting the lateral load of the fluid pressure linear actuator and controlling the driving force of each of the plurality of driving devices so that the lateral load becomes small.

(9)
In the control method of the fluid pressure direct acting actuator according to the ninth aspect of the present invention, in the control method of the composite actuator according to still another aspect, the step (control step) of controlling the driving force of the driving device for each of the plurality of actuators is 1. When pushing two objects to be pressed in cooperation, the driving force in the pushing direction of the actuator arranged in the direction in which the lateral load is detected is increased, and when one object to be pressed is pulled in cooperation, the lateral load is applied. It may be controlled to reduce the driving force in the pulling direction of the actuator arranged in the detected direction.
That is, when pushing one pressurized object in cooperation, it is arranged at one end, reduces the driving force of the fluid pressure linear actuator having a large lateral load in the inward direction, and is arranged at the other end. It may be controlled to increase the driving force of the fluid pressure linear actuator having a large lateral load in the outward direction.

When pushing one object to be pressed in cooperation with multiple fluid pressure linear actuators arranged in parallel with each other, if the displacement of one end is large, the fluid pressure linear actuator at that end is inward. A lateral load is applied, and an outward lateral load is applied to the fluid pressure linear actuator at the other end. Therefore, the direction and magnitude of the lateral load between the fluid pressure linear actuator at one end and the fluid pressure linear actuator at the other end are detected, and the drive of the fluid pressure linear actuator having a large lateral load in the inward direction is detected. By reducing the force and increasing the driving force of the fluid pressure linear actuator having a large lateral load, one object to be pressed can be pushed with a small lateral load.
When pulling one pressurized object in cooperation with a plurality of fluid pressure linear acting actuators arranged in parallel with each other, the driving force of the linear acting actuator having a large lateral load in the inward direction is increased, and the driving force in the outward direction is increased. It is necessary to reduce the driving force of the linear actuator with a large lateral load.

It is a schematic cross-sectional view which shows the structure of the fluid pressure direct-actuator main body of 1st Embodiment. It is a schematic cross-sectional view of the AA'plane of the fluid pressure linear actuator main body of FIG. It is a schematic perspective view which shows an example of the structure of a force sensor. FIG. 4A shows the relationship between the strain gauge, the rod bush and the retainer when there is no lateral load, FIG. 4B shows the relationship when a lateral load is applied downward, and FIG. 4C shows the relationship upward. It is a schematic diagram which shows the relationship when a load is applied. It is a schematic explanatory drawing which shows the relationship between the lateral load in the case of four force sense sensors, and the load applied to each force sense sensor. It is a schematic explanatory drawing which shows the relationship between the lateral load in the case of three force sense sensors, and the load applied to each force sense sensor. It is a schematic block diagram which shows the whole structure of a fluid pressure direct-acting actuator. It is a schematic block diagram which shows the structure of the composite actuator of the 2nd Embodiment. It is a schematic block diagram which shows the other structure of the composite actuator of 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are designated by the same reference numerals. Further, in the case of the same reference numeral, their names and functions are also the same. Therefore, detailed explanations about them will not be repeated.

[First Embodiment]
FIG. 1 is a schematic cross-sectional view showing the structure of the fluid pressure linear motion actuator body 100 of the first embodiment, and FIG. 2 is a schematic cross-sectional view of the AA'plane of the fluid pressure linear motion actuator body 100 of FIG. FIG. 3 is a schematic perspective view showing an example of the configuration of the force sensor 80, FIG. 4 (a) shows the relationship between the strain gauge 85, the rod bush 40, and the retainer 50 when there is no lateral load, and FIG. 4 (b) shows the relationship. FIG. 4C is a schematic diagram showing a relationship when a lateral load is applied in the downward direction and a relationship when a lateral load is applied in the upward direction.
Further, FIG. 5 is a schematic explanatory view showing the relationship between the lateral load when the force sensor 80 is four and the load applied to each force sensor 80, and FIG. 6 is a schematic explanatory view when the force sensor 80 is three. FIG. 7 is a schematic explanatory view showing the relationship between the lateral load of the above and the load applied to each force sensor 80, and FIG. 7 is a schematic block diagram showing the overall configuration of the fluid pressure linear motion actuator 200.

As shown in the cross-sectional view of FIG. 1, the fluid pressure direct acting actuator main body 100 is composed of a piston rod 10, a piston 20, a cylinder tube 30, a rod bush 40, a retainer 50, a dust packing 60, a rod packing 70, a head cover 90, and the like. ing. The rod bush 40 and the retainer 50 form a bearing portion 55 of the piston rod 10.
In the fluid pressure direct acting actuator main body 100 of the present invention, a force sensor 80 is arranged between the rod bush 40 of the bearing portion 55 and the retainer 50 in order to detect the lateral load applied to the bearing portion 55. .. A recess for inserting the force sensor 80 is formed in the outer peripheral portion of the rod bush 40, and the force sensor 80 is formed in the recess formed in the outer peripheral portion of the rod bush 40 at equal intervals in the circumferential direction. One or four are arranged. FIG. 2 shows a case where the force sensor 80 is four. In FIG. 2, for example, when a downward lateral load is applied to the piston rod 10, a load is applied to the force sensor 80 of C, and when a downward lateral load is applied to the piston rod 10, C is applied. And D, a load is applied to the force sensor 80.
In the fluid pressure direct acting actuator main body 100, a mounting bracket for fixing the retainer 50 is arranged on the outside of the retainer 50, and a mounting flange in which the retainer 50 and the mounting bracket are integrated is directly on the outer circumference of the rod bush 40. There is something that covers. In the case of an actuator in which the mounting flange directly covers the outer circumference of the rod bush 40, the force sensor 80 is arranged between the rod bush 40 and the mounting flange.

(Structure and operation of force sensor 80)
As the force sensor 80, a strain gauge 85 attached to the elastic body 82 can be used. FIG. 3 shows an example of the configuration of the force sensor 80. It is desirable that the force sensor 80 is attached to the elastic body 82 so that the longitudinal direction of the strain gauge 85 (the direction in which the resistance change with respect to strain is large) is parallel to the direction in which the lateral load is applied.
As the elastic body 82, it is desirable to use a steel material having an elastic deformation region.
Further, instead of using the elastic body 82, the rod bush 40 may be provided with a recess, and the strain gauge 85 may be directly attached to the recess of the rod bush 40.

FIG. 4A shows the states of the rod bush 40, the force sensor 80, and the retainer 50 when no lateral load is applied from the piston rod 10 to the rod bush 40. Further, FIGS. 4 (b) and 4 (c) show a state when a force F is applied from the piston rod 10 to the rod bush 40. When a downward force F is applied as shown in FIG. 4B, the gap between the rod bush 40 and the retainer 50 becomes smaller, and the force sensor 80 is compressed in the vertical direction by that amount. On the other hand, when an upward force F is applied as shown in FIG. 4C, the gap between the rod bush 40 and the retainer 50 becomes large, but there is also a gap between the force sensor 80 and the retainer 50. Yes, the shape of the force sensor 80 does not change. Therefore, the force sensor 80 of FIG. 4 changes its output (resistance value of the strain gauge 85) only when the force F is applied downward.

(Method of detecting the magnitude and direction of lateral load by multiple force sensors)
FIG. 5 shows the relationship between the lateral load when there are four force sensors 80 and the load applied to each force sensor 80, and FIG. 6 shows the lateral load when there are three force sensors 80. And the load applied to each force sensor 80 are shown.
FIG. 5 shows the force applied to the force sensor 80 of C when the force F is between C and D of the four force sensors 80 and the angle with C is applied in the direction of θ. The force F2 applied to the force sensor 80 of F1 and D is shown.
From FIG. 5, F1 = Fcos (θ) and F2 = Fsin (θ).
Therefore, the force F is

で表される。また、力ＦとＣ方向とのなす角度θは、 (Equation 1)

It is represented by. Further, the angle θ formed by the force F and the C direction is

で表される。 (Equation 2)

It is represented by.

FIG. 6 shows the force applied to the force sensor 80 of C when the force F is between B and C of the three force sensors 80 and the angle with C is applied in the direction of θ. The force F2 applied to the force sensor 80 of F1 and D is shown.
In this case, the area S of the parallelogram is
S = F1 × F2 × sin (120 °)
S = F × F1 × sin (θ)
S = F × F2 × sin (120 ° -θ)
By combining these, the angle θ between the forces F and the C direction can be calculated by.

で表される。また、力Ｆの大きさは、上記θを用いて、 (Equation 3)

It is represented by. Further, the magnitude of the force F is determined by using the above θ.

で表される。 (Equation 4)

It is represented by.

(Overall configuration of fluid pressure direct acting actuator 200)
FIG. 7 shows the configuration of the fluid pressure direct acting actuator 200 including the fluid pressure direct acting actuator main body 100 and the display device 130. The display device 130 includes a control circuit 110 and a display device 120, and is A, B, C, and D of the force sensor 80 (A, B, and C when the force sensor 80 is three). The output of is input to the display device 130, and the magnitude F and the angle θ of the lateral load are calculated by the control circuit 110. The calculated lateral load magnitude F and angle θ are displayed on the display 120 and output to the external remote monitoring device 140. As the remote monitoring device 140, for example, a personal computer, a smartphone, or the like can be used. Further, the fluid pressure direct acting actuator 200 is driven by the driving device 210.

(Centering (shaft alignment) method)
Conventionally, the fluid pressure direct acting actuator 200 has been installed by the following method in order to center (shaft alignment) the piston rod 10 and the bearing portion 55.
Step 1: Temporarily fix the piston rod 10 to the device while it is pulled into the cylinder tube 30.
Step 2: Check if the centering is done.
As a method for confirming whether or not the centering is completed, for example, the following method is used.
a) The fluid pressure linear actuator 200 is operated, and chattering occurs during the operation of the piston rod 10 (stick slip: self-excited vibration caused by microscopic friction surface adhesion between friction surfaces and repeated sliding). Make sure there is no.
b) When the mounting direction of the fluid pressure linear actuator 200 is vertically downward, the octopus thread is hung on the fluid pressure linear actuator body 100, and the cylinder tube 30 and the piston rod 10 pulled out from the cylinder tube 30 are both in the vertical direction. Make sure there is.
c) A dial gauge is applied to the piston rod 10 to operate the fluid pressure direct acting actuator main body 100, and it is confirmed that the dial of the dial gauge does not run out.
Step 3: If there is misalignment, adjust so that the misalignment is eliminated.
As a method for adjusting this misalignment, for example, the following method is used.
d) A shim (thin plate for adjusting the spacing) is sandwiched between the device fixing the linear actuator and the bearing portion 55.
e) If there is an adjustment mechanism such as an adjuster bolt on the device side, the tilt of the device side mounting plate is adjusted by the adjustment mechanism.

In the fluid pressure direct acting actuator 200 of the first embodiment, the above steps 2 and 3 can be performed more easily and with high accuracy. Specifically, the magnitude and direction of the lateral load (output of the force sensor 80) are detected with the piston rod 10 pulled out from the cylinder tube 30.
When a lateral load is detected above a certain level, a shim is inserted between the bearing portion 55 in the direction in which the lateral load is detected and the device, or a shim is inserted between the bearing portion 55 and the device by the adjusting mechanism. Increase the distance.
After that, the lateral load is detected again, and further adjustment is continued if necessary.
In this method, since the magnitude and direction of the lateral load can be visually recognized, adjustment can be made while observing the detection result of the lateral load.

The piston rod 10 of the fluid pressure direct acting actuator main body 100 may receive an unexpectedly large lateral load or a lateral load from an unexpected direction due to contact with a surrounding structure or the like. Further, even during normal work, a large lateral load may be applied to the bearing portion 55 due to wear of the bearing or the like.
In order to quickly respond to these unexpected lateral loads, the fluid pressure linear actuator 200 of the present embodiment detects a load value outside the appropriate range and / or is out of the appropriate range. When the lateral load in the direction is detected, the warning signal is displayed on the display 120 of the display device 130, and the warning signal is output by voice or the like. Further, it is desirable to send a stop signal to the drive device 210 for driving the fluid pressure linear actuator 200 to stop the drive of the fluid pressure linear actuator 200.
When the display device 130 is connected to the remote monitoring device 140, it is desirable to transmit an alarm signal to the remote monitoring device 140.
The display device 130 may be connected to the fluid pressure direct acting actuator main body 100 only when necessary, for example, when it is not necessary to constantly monitor the lateral load.

[Second Embodiment]
FIG. 8 is a schematic block diagram showing the configuration of the composite actuator 250 of the second embodiment. The composite actuator 250 of FIG. 8 is composed of two fluid pressure direct acting actuator main bodies 100a and 100b, a control device 220, and two drive devices 210a and 210b. The drive devices 210a and 210b are composed of a bidirectional pump and a bidirectional motor.
Since the fluid pressure direct acting actuator main body 100 of the first embodiment can output the magnitude and direction of the lateral load, for example, the fluid pressure direct acting actuator main body 100a is the fluid pressure direct acting actuator main body 100 of the first embodiment. The fluid pressure linear actuator main body 100b may be an actuator without a lateral load detection function.
In the composite actuator 250 of FIG. 8, the piston rods 10a and 10b of the fluid pressure linear acting actuator main bodies 100a and 100b are fixed to one pressurized object 230 and push up the pressurized object 230 in cooperation with each other. In this case, for example, if the force pushing up the pressurized object 230 of the fluid pressure direct acting actuator main body 100a is larger than the force of the fluid pressure direct acting actuator main body 100b and the piston rod 10b is pushed upward above the piston rod 10a, A lateral load facing left is applied to the piston rods 10a and 10b. When a lateral load facing left is applied, the lateral load of the piston rods 10a and 10b is applied to the dust packing 60 and the rod packing 70 (see FIG. 1) of the bearing portion 55, and the wear of the packing further causes a fluid leak. There is a possibility of connecting. Further, in this case, distortion occurs inside the composite actuator 250, which may cause a failure such as breakage of a part due to metal fatigue.
In order to avoid applying the lateral load to the piston rods 10a and 10b, it is necessary to adjust the balance of the driving force of the driving devices 210a and 210b.

In the composite actuator 250 of the second embodiment, the control device 220 obtains information on the magnitude and direction of the lateral load from the fluid pressure direct acting actuator main body 100a (or the fluid pressure direct acting actuator main body 100a and the fluid pressure direct acting actuator main body 100b). The control device 220 adjusts the driving force of the driving devices 210a and 210b so that the lateral load is not applied to the piston rods 10a and 10b.
Specifically, for example, when the composite actuator 250 provided with two fluid pressure direct acting actuator main bodies 100a and 100b pushes up the pressurized object 230, it faces to the left (outward direction of the fluid pressure direct acting actuator main body 100a and fluid pressure direct movement). When a lateral load (inward direction of the dynamic actuator body 100b) is detected, the driving force of the drive device 210b for driving the fluid pressure direct acting actuator body 100b on the right side is reduced, and when a lateral load pointing to the right is detected. By increasing the driving force of the driving device 210b that drives the fluid pressure linear actuator main body 100b on the right side, it is possible to prevent the lateral load from being applied to the piston rods 10a and 10b.
Further, when the composite actuator 250 cooperates to pull one pressurized object 230, when a leftward lateral load is detected, the drive device 210b for driving the fluid pressure direct acting actuator main body 100b on the right side is driven. A lateral load is applied to the piston rods 10a and 10b by increasing the force and decreasing the driving force of the drive device 210b that drives the right fluid pressure linear actuator body 100b when a rightward lateral load is detected. It can be prevented from being done.
Further, in the present embodiment, the number of the fluid pressure direct acting actuator main bodies 100a and 100b is two, but the number may be increased, for example, three. In this case, the lateral load can be reduced by adjusting the driving force of the fluid pressure linear actuator at one end and the fluid pressure linear actuator at the other end.

FIG. 9 is a schematic block diagram showing another configuration of the composite actuator 250 of the second embodiment. In FIG. 8, the drive devices 210a and 210b composed of the bidirectional pump and the bidirectional motor are connected to the fluid pressure direct acting actuator main bodies 100a and 100b, respectively, whereas in FIG. 9, the fluid pressure direct acting actuator is connected. Switching valves 260a and 260b having a proportional control function are inserted between each of the main bodies 100a and 100b and the drive device 210 composed of a one-way pump and a one-way motor. Further, when controlling the fluid pressure direct acting actuator main bodies 100a and 100b with higher accuracy, it is desirable to change the switching valves 260a and 260b to servo valves.

In this case, in the composite actuator 250 including two or more linear actuators 200, it is most preferable that all the linear actuators 200 are controlled so that the lateral load becomes zero (close to zero). Alternatively, the total value of the lateral load values of each linearly driven actuator 200 may be controlled to be the minimum.
Alternatively, when there are three or more linear actuators 200, the lateral load value is projected by controlling the actuator that maximizes the lateral load and / or the linear actuator 200 that minimizes the lateral load. It may be controlled to reduce the number of the dynamic actuators 200.
In this way, the operating amount of each linear actuator 200 can be adjusted during the installation work of the composite actuator 250.
Further, when operating the composite actuator 250, the center of gravity (point of action) of the object to be pressurized 230 and the force point of the composite actuator 250 may not match. Then, since a different reaction force is generated for each linear actuator 200, the operating amount changes for each linear actuator 200, and a lateral load may be generated. In such a case, the operating amount of each actuator can be made uniform by controlling the lateral load to be smaller according to the object to be pressurized 230. As a result, the force of each linear actuator 200 can be reliably and efficiently transmitted to the pressurized object 230, and the failure of the composite actuator 250 can be prevented.

In the present invention, the force sensor 80 corresponds to the "force sensor", the bearing portion 55 corresponds to the "bearing portion", the fluid pressure direct acting actuator bodies 100, 100a, 100b, and the fluid pressure direct acting actuator 200. Corresponds to the "fluid pressure direct acting actuator", the display device 130 corresponds to the "display device", the rod bush 40 corresponds to the "rod bush", the retainer 50 corresponds to the "retainer", and the strain gauge 85 corresponds to the strain gauge 85. The piston rods 10, 10a and 10b correspond to the "strain gauge", the pressurized object 230 corresponds to the "pressurized object", and the drive devices 210, 210a and 210b "drive". The control device 220 corresponds to the "control device", and the composite actuator 250 corresponds to the "composite actuator".

A preferred embodiment of the present invention is as described above, but the present invention is not limited thereto. It will be appreciated that various embodiments are made that do not deviate from the spirit and scope of the invention. Further, in the present embodiment, the actions and effects according to the constitution of the present invention are described, but these actions and effects are examples and do not limit the present invention.

10 Piston rod 40 Rod bush 50 Retainer 55 Bearing part 80 Force sensor 85 Strain gauge 100, 100a, 100b Fluid pressure direct acting actuator body 130 Display device 200 Fluid pressure direct acting actuator 210, 210a, 210b Drive device 220 Control device 230 Pressurized object 250 compound actuator

Claims (9)

A fluid pressure direct acting actuator that has a plurality of force sensors built in the bearing portion in the circumferential direction and outputs the magnitude and direction of the lateral load applied to the bearing portion. The bearing portion is composed of a cylindrical rod bush and a retainer or a mounting flange that covers the outer circumference of the rod bush.
The fluid pressure direct acting actuator according to claim 1, wherein the force sensor is a strain gauge and is disposed between the rod bush and the retainer or the mounting flange. The force sense sensors are three or four, and are arranged at equal intervals in the circumferential direction of the bearing portion.
The magnitude and direction of the lateral load applied to the bearing portion are calculated based on the force detected by two of the plurality of force sensors, according to claim 1 or 2. The fluid pressure direct acting actuator described. In addition, it is equipped with a display device.
The third aspect of claim 3, wherein the display device displays and / or outputs the load value and direction of the lateral load by inputting the specifications of the target piston rod and the force sensor. Fluid pressure direct acting actuator. The display device constantly monitors the load value of the lateral load, outputs an alarm signal when a load value outside the appropriate range is detected, and / or outputs a stop signal to the drive device of the fluid pressure linear actuator. The fluid pressure direct acting actuator according to claim 4. The fluid pressure direct acting actuator according to claim 4 or 5, wherein the display device constantly monitors the direction of the lateral load and outputs an alarm signal when the lateral load in a direction outside the appropriate range is detected. Multiple actuators that are arranged parallel to each other and work together to push and pull one pressurized object,
A drive device that drives each of the plurality of actuators,
A control device for controlling the drive device is provided.
The plurality of actuators include the fluid pressure direct acting actuator according to any one of claims 1 to 3, and the fluid pressure direct acting actuator outputs the magnitude and direction of the lateral load to the control device.
The control device is a composite actuator that controls the drive device so that the magnitude of the lateral load of the fluid pressure direct acting actuator becomes small. A composite including a plurality of actuators arranged in parallel with each other and cooperating to push and pull one pressurized object, a drive device for driving each of the plurality of actuators, and a control device for controlling the drive device. It ’s an actuator control method.
At least one of the plurality of actuators is a fluid pressure direct acting actuator, and the step of detecting the magnitude and direction of the lateral load by the fluid pressure direct acting actuator and inputting the input to the control device.
A method for controlling a composite actuator, comprising a step of controlling the driving force of the driving device with respect to each of the plurality of actuators so that the control device reduces the magnitude of the lateral load. The step of controlling the driving force of the driving device for each of the plurality of actuators is
When pushing one pressurized object in cooperation, the driving force in the pushing direction of the actuator arranged in the direction in which the lateral load is detected is increased.
The composite actuator according to claim 8, wherein when one pressurized object is pulled in cooperation with each other, the driving force in the pulling direction of the actuator arranged in the direction in which the lateral load is detected is controlled to be reduced. Control method.

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