Electric actuator, thrust force deriving method for electric actuator, and program

Abstract

To enable the output of an electric actuator that suppresses the influence of a load due to the internal pressure in consideration of the internal pressure change that accompanies the operation of the electric actuator.SOLUTION: An electric actuator includes a housing, a motor, a screw shaft to which the rotational force of the motor is input, a connecting mechanism configured to linearly move along the screw shaft as the screw shaft rotates due to the rotational force, a hollow output shaft that is connected to the connecting mechanism and linearly moves together with the connecting mechanism to output thrust, a pressure sensor configured by the output shaft and the housing and configured to detect pressure in a sealed space in which the connecting mechanism is arranged, a control unit that controls the operation of the motor, and a derivation unit that derives the thrust generated by the output shaft on the basis of the pressure detected by the pressure sensor and the amount of control of the motor by the control unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electric actuator, a thrust deriving method for an electric actuator, and a program. [Background technology]

[0002] 2. Description of the Related Art Recently, electric actuators that are configured to convert the rotational force of a motor into linear thrust and operate the actuator have become widespread.

[0003] In an electric actuator, the control amount is determined based on the input, but a technique has been disclosed for adjusting the control amount even for the same input, taking into account the influence of the operating environment, etc. For example, Patent Document 1 describes switching the threshold value for controlling an electric brake according to the input pedal force. Also, Patent Document 2 describes switching the threshold value for controlling an electric actuator according to the temperature. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-11703 A [Patent Document 2] JP 2013-154843 A Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, the electric actuator as described above may have a waterproof or dustproof structure in consideration of the environment in which it is used. For example, electric actuators for control used in railways are used outdoors, so it is necessary to prevent rainwater and dust from entering the inside of the electric actuator. In the case where the housing member of the electric actuator and the output shaft part are configured to perform piston movement via a connecting member, assuming use in such an environment, a waterproof structure for preventing water from entering around the connecting member can be mentioned. In such a structure, a sealed space is formed around the connecting member. The volume of the sealed space varies with the operation of the electric actuator. This causes the pressure in the sealed space to vary, which affects the operation of the electric actuator. In other words, in the case of the above-mentioned waterproof or dustproof structure, it becomes difficult to exchange air between the inside and outside, so the air inside is compressed by the operation of the electric actuator, which can become a load that inhibits the operation. As a result, even if the control amount is the same, the output by the electric actuator will be different. In this way, it is important to understand the actual output of the electric actuator by assuming a case where the same control amount results in different outputs in order to operate the electric actuator with high precision.

[0006] In view of the above problems, an object of the present invention is to enable output from an electric actuator while suppressing the effects of load due to internal pressure, taking into account internal pressure changes that accompany the operation of the electric actuator. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention has the following configuration. Housing and A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a pressure sensor configured by the output shaft and the housing and configured to detect a pressure in a sealed space in which the connecting mechanism is disposed; A control unit for controlling the operation of the motor; a deriving unit that derives a thrust force from the output shaft based on the pressure detected by the pressure sensor and a control amount of the motor by the control unit; An electric actuator comprising:

[0008] Another aspect of the present invention has the following configuration. Housing and A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a temperature sensor configured by the output shaft and the housing and configured to detect a temperature of a sealed space in which the connecting mechanism is disposed; A control unit for controlling the operation of the motor; a derivation unit that derives a thrust force by the output shaft based on the temperature detected by the temperature sensor and a control amount of the motor by the control unit; An electric actuator comprising:

[0009] Another aspect of the present invention has the following configuration. Housing and A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a pressure sensor configured by the output shaft and the housing and detecting a pressure in a sealed space in which the connecting mechanism is disposed; A method for generating thrust of an electric actuator comprising: A thrust deriving method for an electric actuator, comprising the steps of: deriving thrust by the output shaft based on the pressure detected by the pressure sensor and a control amount of the motor.

[0010] Another aspect of the present invention has the following configuration. Housing and A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a temperature sensor configured by the output shaft and the housing, and detecting a temperature of a sealed space in which the connecting mechanism is disposed; A method for generating thrust of an electric actuator comprising: A method for deriving thrust force of an electric actuator, comprising the steps of: deriving thrust force by the output shaft based on a temperature detected by the temperature sensor and a control amount of the motor.

[0011] Another aspect of the present invention has the following configuration. Housing and A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a pressure sensor configured by the output shaft and the housing and detecting a pressure in a sealed space in which the connecting mechanism is disposed; A control device for an electric actuator comprising: A program for deriving thrust from the output shaft based on the pressure detected by the pressure sensor and the control amount of the motor.

[0012] Another aspect of the present invention has the following configuration. Housing and A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a temperature sensor configured by the output shaft and the housing, and detecting a temperature of a sealed space in which the connecting mechanism is disposed; A control device for an electric actuator comprising: A program for deriving thrust force from the output shaft based on the temperature detected by the temperature sensor and the control amount of the motor. Effect of the Invention

[0013] According to the present invention, it is possible to output an electric actuator while suppressing the effect of load due to internal pressure by taking into account internal pressure changes that accompany the operation of the electric actuator. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing an example of an apparatus configuration according to a first embodiment. [Diagram 2] FIG. 4 is a diagram for explaining pressure inside the electric actuator according to the embodiment of the present invention. [Diagram 3] FIG. 4 is a diagram for explaining pressure inside the electric actuator according to the embodiment of the present invention. [Figure 4] 1 is a diagram for explaining movement inside an electric actuator according to an embodiment of the present invention. FIG. [Diagram 5] FIG. 4 is a graph illustrating the relationship between the volume, the internal pressure, and the stroke distance of a sealed space according to an embodiment of the present invention. [Figure 6]FIG. 4 is a graph illustrating the effect of a change in stroke distance on a thrust force of the electric actuator according to the embodiment of the present invention. [Figure 7] FIG. 4 is a graph illustrating the effect of a change in stroke distance on a thrust force of the electric actuator according to the embodiment of the present invention. [Figure 8] 4 is a flowchart of a control process for the electric actuator according to the first embodiment. [Figure 9] FIG. 11 is a schematic diagram showing an example of an apparatus configuration according to a second embodiment. [Figure 10] 10 is a flowchart of a control process for an electric actuator according to a second embodiment. [Figure 11] FIG. 11 is a schematic diagram showing an example of an apparatus configuration according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiment for carrying out the present invention will be described with reference to the drawings. Note that the embodiment described below is one embodiment for explaining the present invention, and is not intended to be interpreted as limiting the present invention, and all configurations described in each embodiment are not necessarily essential configurations for solving the problems of the present invention. In addition, in each drawing, the same components are given the same reference numbers to indicate their correspondence.

[0016] <First embodiment> A first embodiment of the present invention will be described below.

[0017] [Device configuration] Fig. 1 is a schematic diagram showing an example of the overall configuration of the device according to this embodiment. In Fig. 1, an electric actuator 10 according to this embodiment is configured to include a drive unit 100 and a control device 200. The control device 200 is also communicatively connected to a host device 20 that is positioned above the electric actuator 10. The electric actuator 10 operates based on instructions from the host device 20.

[0018] The driving unit 100 outputs a predetermined thrust based on the control of the control device 200. The motor 102 rotates based on a current input from the control device 200. The motor 102 includes a rotational position sensor 103. The rotational position sensor 103 detects a rotational position associated with the rotational operation of the motor 102 using an encoder (not shown) or the like, and transmits the detected rotational position to the control device 200. A reducer 104 for transmitting the rotational force of the motor 102 is provided inside the housing 101. The reducer 104 is connected to a linear motion mechanism 108, and the rotational force from the reducer 104 is transmitted to the linear motion mechanism 108. The output shaft 105 and the linear motion mechanism 108 are connected via a connecting mechanism 107. When the linear motion mechanism 108 rotates, the connecting mechanism 107 moves along the axial direction of the linear motion mechanism 108 (the direction indicated by the arrow A in FIG. 1), and the output shaft 105 also moves (piston operation) in accordance with this, so that the thrust by the electric actuator 10 is output. The direction of movement of the output shaft 105 and the connecting mechanism 107 is determined according to the direction of rotation of the motor 102 .

[0019] The linear motion mechanism 108 is configured with a screw shaft having a helical screw groove on its outer circumferential surface. The connecting mechanism 107 is arranged by being fitted into the screw groove. At this time, a rolling element (not shown) included in the connecting mechanism 107 is configured to be able to roll freely in the screw groove of the linear motion mechanism 108, and the connecting mechanism 107 moves in a predetermined direction as the linear motion mechanism 108 rotates. A lubricant (lubricating oil, grease, etc.) may be supplied around the rolling element and the screw groove by any lubrication method to reduce friction therebetween.

[0020] The housing 101 and the output shaft 105 form a sealed space 109 including the connecting mechanism 107 and the linear motion mechanism 108. That is, in this embodiment, it is assumed that the sealed space 109 formed by the housing 101 and the output shaft 105 is configured to prevent the inflow of liquid or the like into the sealed space 109. By providing the sealed space, dustproofing and waterproofing can be realized, but it becomes difficult to exchange air with the outside. A pressure sensor 106 for detecting the pressure in the sealed space 109 is provided in the sealed space 109. In FIG. 1, the sealed spaces 109 are shown on both sides of the connecting mechanism 107, but these are connected to form one sealed space 109. Here, it is described that the pressure sensor 106 detects air pressure, but a sensor that detects a liquid pressure (e.g., oil pressure) may be used depending on the configuration of the electric actuator 10. The pressure sensor 106 transmits information on the detected pressure to the control device 200.

[0021] The control device 200 is connected to the higher-level device 20 so as to be able to communicate with it. The control device 200 may be composed of, for example, a central processing unit (CPU), a micro processing unit (MPU), a digital single processor (DSP), or a dedicated circuit. Although not shown in FIG. 1, the control device 200 is composed of volatile and non-volatile storage media such as a hard disk drive (HDD), a read only memory (ROM), and a random access memory (RAM). Although FIG. 1 shows one higher-level device 20 and one electric actuator 10, the present invention is not limited to this, and one higher-level device 20 may control and manage multiple electric actuators 10.

[0022] The motor braking unit 201 outputs a signal for controlling the motor 102 to the inverter 202 according to an instruction from the higher-level device 20. The inverter 202 converts the power supplied from the power source 203 into a current for operating the motor 102 based on the signal from the motor braking unit 201 and supplies the current to the motor 102. The motor 102 rotates based on the supplied current. Note that the inverter 202 and the power source 203 are shown as components provided in the control device 200, but they may be provided outside the control device 200.

[0023] The thrust derivation unit 204 derives a thrust output from the electric actuator 10 as a result of operating the motor 102. A thrust derivation method according to this embodiment will be described later. The motor angle derivation unit 205 derives a rotation angle of the motor 102 based on position information acquired from a rotation position sensor 103 provided in the motor 102. Here, the configuration may be such that the rotation speed of the motor 102 is also derived. The current sensor 206 detects a current supplied to the motor 102 by the inverter 202. The state monitoring unit 207 collects various information from various sensors and parts, and monitors the states of the drive unit 100 and the control device 200. In addition, the state monitoring unit 207 transmits the monitoring results (presence or absence of an abnormality, operating status, etc.) to the state output unit 208. The state output unit 208 outputs the information acquired from the state monitoring unit 207 to the upper device 20.

[0024] The higher-level device 20 may be realized, for example, by an information processing device including a control unit, a storage unit, and an input / output unit (not shown). The control unit may be composed of a CPU, an MPU, a DSP, an ECU (Electronic Control Unit), or a dedicated circuit. The storage unit is composed of volatile and non-volatile storage media such as a HDD, a ROM, and a RAM, and is capable of inputting and outputting various information in response to instructions from the control unit. The input / output unit may be composed of various interfaces, and is at least connected to the control device 200 so as to be able to communicate with them.

[0025] [Pressure changes in a sealed space] 2 and 3 are diagrams for explaining the change in pressure in the sealed space 109 configured in the electric actuator 10 according to this embodiment and its influence. FIG. 2(a) shows a case where the output shaft 105 in the driving unit 100 operates in the extension direction from the most contracted state. At this time, it is assumed that the control device 200 receives an instruction from the upper device 20 with the thrust by the driving unit 100 as a thrust P1a in the extension direction. In the state of FIG. 2(a), the sealed space 109 of the driving unit 100 is compressed, and as a result, the internal pressure of the sealed space 109 increases. Therefore, the force P2a in the extension direction due to the internal pressure in the sealed space 109 is combined with the thrust P1a of the driving unit 100 controlled based on the instruction. As a result, the thrust output by the driving unit 100 becomes P3a (=P1a+P2a).

[0026] FIG. 2(b) shows a case where the output shaft 105 of the drive unit 100 operates in the extension direction from a state where it is extended to a certain extent. At this time, it is assumed that the control device 200 receives an instruction from the upper device 20, regarding the thrust by the drive unit 100 as a thrust P1b in the extension direction. In the state of FIG. 2(b), the volume of the sealed space 109 of the drive unit 100 is expanded compared to the state of FIG. 2(a), and as a result, the internal pressure of the sealed space 109 is reduced. Therefore, the force P2b due to the internal pressure in the sealed space 109 is combined with the thrust P1b of the drive unit 100 controlled based on the instruction. Here, as an example, the force P2b due to the internal pressure is shown to be in the opposite (-) direction to the thrust of the drive unit 100 (i.e., the contraction direction). As a result, the thrust output by the drive unit 100 becomes P3b (=P1b-P2b).

[0027] 2(b), the volume of the sealed space 109 becomes larger than that of the state of Fig. 2(a), and the internal pressure of the sealed space 109 changes accordingly, changing the degree of influence on the thrust force output by the drive unit 100. Note that, as shown by force P2b in Fig. 2(b), whether or not a force is generated in the direction opposite to the direction in which the output shaft 105 extends varies depending on the volume of the sealed space 109, the configuration of the electric actuator 10, and the like.

[0028] FIG. 3(a) shows a case where the output shaft 105 of the driving unit 100 operates in the contraction direction from a contracted state to a certain extent. At this time, it is assumed that the control device 200 receives an instruction from the upper device 20 with the thrust by the driving unit 100 as a thrust P1c in the contraction direction. In the state of FIG. 3(a), the sealed space 109 of the driving unit 100 is compressed, and as a result, the internal pressure of the sealed space 109 increases. Therefore, the force P2c due to the internal pressure in the sealed space 109 is combined with the thrust P1c of the driving unit 100 controlled based on the instruction. Here, as an example, a case is shown where the force P2c due to the internal pressure is in the opposite (-) direction to the thrust of the driving unit 100 (i.e., the extension direction). As a result, the thrust output by the driving unit 100 becomes P3c (=P1c-P2c).

[0029] FIG. 3(b) shows a case where the output shaft 105 of the drive unit 100 contracts from a state in which it is extended to a certain extent. At this time, it is assumed that the control device 200 receives an instruction from the upper device 20, regarding the thrust by the drive unit 100 as a thrust P1d in the contraction direction. In the state of FIG. 3(b), the volume of the sealed space 109 of the drive unit 100 is expanded compared to the state of FIG. 3(a), and as a result, the internal pressure of the sealed space 109 is reduced. Therefore, the force P2d in the contraction direction due to the internal pressure in the sealed space 109 is combined with the thrust P1d of the drive unit 100, which is controlled based on the instruction. As a result, the thrust output by the drive unit 100 becomes P3d (=P1d+P2d).

[0030] That is, in the state of Fig. 3(b), the volume of the sealed space 109 becomes larger than in the state of Fig. 3(a), and the internal pressure of the sealed space 109 changes accordingly, changing the degree of influence on the thrust force output by the driving unit 100. Note that, as shown by force P2d in Fig. 3(b), whether or not a force is generated in the same direction as the contraction direction of the output shaft 105 varies depending on the volume of the sealed space 109, the configuration of the electric actuator 10, and the like.

[0031] FIG. 4 is a diagram for explaining the operation of the drive unit 100 around the output shaft 105. The connecting mechanism 107 is configured to be movable within the sealed space 109 along the linear motion mechanism 108 within a movable range shown in FIG. 4. When the connecting mechanism 107 moves in the contraction direction shown in FIG. 4, the volume of the sealed space 109 decreases. On the other hand, when the connecting mechanism 107 moves in the extension direction, the volume of the sealed space 109 increases. Here, the pressure sensor 106 is omitted. The movable range can vary depending on the arrangement of the pressure sensor 106, etc.

[0032] 4, the center of the movable range of the connecting mechanism 107 in the moving direction is set as a reference position P0. Also, in the moving direction of the connecting mechanism 107, the center of the connecting mechanism 107 is set as a central position P c Then, the reference position P0 and the central position P c The distance between the stroke distance (=P0-P c In this example, the central position P c When the reference position P0 is located on the contraction side, the stroke distance indicates a negative value, and the central position P c is located on the enlargement direction side of the reference position P0, the stroke distance indicates a positive value. Note that the method of calculating the stroke distance is not limited to this. For example, the reference position P0 may be set at the end of the movable range, or the end of the connecting mechanism 107 may be used instead of the central position Pc.

[0033] 5 is a diagram for explaining the relationship between the volume, stroke distance, and internal pressure of the sealed space 109 of the driving unit 100 according to this embodiment. In FIG. 5(a), the horizontal axis indicates the stroke distance, and the vertical axis indicates the volume of the sealed space 109. The stroke distance L min Then, the volume of the sealed space 109 is the minimum volume V min In addition, the stroke distance L max Then, the volume of the sealed space 109 is the maximum volume V maxAs shown in FIG. 5, as the stroke distance increases, the volume of the sealed space 109 also increases. When the stroke distance is 0, that is, when the center position P c The volume when the reference position P0 coincides with the reference position P1 is defined as the volume V0.

[0034] In Fig. 5(b), the horizontal axis indicates the volume of the sealed space 109, and the vertical axis indicates the internal pressure of the sealed space 109. max In this case, the internal pressure of the sealed space 109 is the minimum internal pressure P min In addition, the volume of the sealed space 109 is the minimum volume V min In this case, the internal pressure of the sealed space 109 is the maximum internal pressure P max The relationship shown in Fig. 5(b) can be derived from the configuration of the electric actuator 10 and Boyle's law, etc.

[0035] 6 and 7 are diagrams for explaining the effect of the internal pressure of the sealed space 109 of the drive unit 100 on the thrust force and the relationship with the stroke distance. In FIG. 6, the vertical axis indicates the amount of change (force) in the thrust force due to the internal pressure in the extension direction, and the horizontal axis indicates the stroke distance. That is, FIG. 6 shows the relationship between the thrust force and the stroke distance during the extension operation described with reference to FIG. 2. Stroke distance L min So, what is the maximum change amount ΔF? max In addition, the stroke distance L max So, what is the minimum change amount ΔF? min In this example, when the stroke distance is 0, the amount of change is 0, and there is no effect on the thrust that the electric actuator 10 wishes to output. When the amount of change indicates a negative value, a force acts in the opposite direction to the direction of the thrust that the electric actuator 10 wishes to output, as shown in FIG. 2(b). On the other hand, when the amount of change indicates a positive value, a force acts in the same direction as the direction of the thrust that the electric actuator 10 wishes to output, as shown in FIG. 2(a).

[0036] In FIG. 7, the vertical axis indicates the change (force) in thrust due to the internal pressure in the contraction direction, and the horizontal axis indicates the stroke distance. That is, FIG. 7 shows the relationship between thrust and stroke distance during the contraction operation described with reference to FIG. 3. Stroke distance L min So, what is the minimum change amount ΔF? min In addition, the stroke distance L max So, what is the maximum change amount ΔF? max In this example, when the stroke distance is 0, the amount of change is 0, and there is no effect on the thrust force that the electric actuator 10 wishes to output. When the amount of change indicates a negative value, a force acts in the opposite direction to the direction of the thrust force that the electric actuator 10 wishes to output, as shown in FIG. 3(a). On the other hand, when the amount of change indicates a positive value, a force acts in the same direction as the direction of the thrust force that the electric actuator 10 wishes to output, as shown in FIG. 3(b).

[0037] Note that the relationships between the parameters shown in Figures 5 to 7 are merely examples and are not intended to be limiting. For example, the gradients of the straight lines and the curvatures of the curves shown in Figures 5 to 7 may vary depending on the configuration of the electric actuator 10 and the ambient temperature.

[0038] [Processing flow] 8 is a flowchart of the control process of the electric actuator 10 according to this embodiment. This process is executed by the control device 200, for example, by reading out from a storage device (not shown) and executing a program for implementing each part shown in FIG.

[0039] In S801, the control device 200 receives an operation instruction for the electric actuator 10 from the higher-level device 20. The operation instruction here may be, for example, a thrust value to be output by the electric actuator 10, or a movement amount of the output shaft 105.

[0040] In S802, the control device 200 outputs a current for operating the motor 102 based on the operation instruction received in S801. The current here is supplied to the motor 102 after being converted by the inverter 202 from the power source 203 based on a signal instructed by the motor braking unit 201.

[0041] In S803, the control device 200 acquires the value of the current supplied to the motor 102 by the current sensor 206.

[0042] In S804, the control device 200 derives the torque by the motor 102 from the current value acquired in S803. The derivation method here is not particularly limited, but may be performed by referring to a table (not shown) that associates current with torque, or may be performed by using a predefined calculation formula, for example.

[0043] In S805, the control device 200 acquires the internal pressure of the sealed space 109 by the pressure sensor .

[0044] In S806, the control device 200 causes the thrust derivation unit 204 to derive the thrust of the output shaft 105 based on the torque derived in S804 and the internal pressure acquired in S805. First, the thrust derivation unit 204 derives the thrust from the torque derived in S804. Here, the thrust may be derived by referring to a table (not shown) in which the torque and the thrust are associated with each other, or may be derived using a predefined calculation formula. Next, the thrust derivation unit 204 derives a change amount ΔF in the thrust from the internal pressure acquired in S805 based on the relationship as described in FIG. 6 and FIG. 7. Then, the thrust derivation unit 204 derives the thrust by the output shaft 105 by combining the thrust based on the torque and the change amount. Then, this processing flow ends.

[0045] The control device 200 may be configured to adjust the rotational operation of the motor 102 based on the thrust derived in S806 of Fig. 8. Also, the control device 200 may be configured to output information on the derived thrust to the higher-level device 20 via the status output unit 208.

[0046] For example, when a difference occurs between the thrust based on the operation command and the thrust output due to the influence of a change in internal pressure, the torque of the motor 102 is adjusted to offset the difference. This feedback function controls the thrust based on the operation command to be equal to the thrust actually output, regardless of the change in internal pressure of the sealed space. In other words, even if a load that inhibits the operation of the electric actuator 10 occurs due to the provision of the sealed space, it is possible to reduce the influence and output the thrust based on the operation command.

[0047] As described above, according to this embodiment, it is possible to output an electric actuator while suppressing the effect of the load due to the internal pressure, taking into account the internal pressure changes that accompany the operation of the electric actuator.

[0048] <Second embodiment> A second embodiment of the present invention will be described below. In the first embodiment, the pressure sensor 106 was used to detect the state of the sealed space 109 of the electric actuator 10. In this embodiment, a configuration in which a temperature sensor 901 is used instead of the pressure sensor 106 will be described. Note that descriptions of parts that overlap with the first embodiment will be omitted, and the description will focus on the differences.

[0049] [Device configuration] Fig. 9 is a schematic diagram showing an example of the overall configuration of the device according to this embodiment. The difference from the configuration shown in Fig. 1 is that a temperature sensor 901 is provided in place of the pressure sensor 106 in the sealed space 109 of the electric actuator 10. In addition, the control device 200 further includes a pressure lead-out unit 902.

[0050] The temperature sensor 901 detects the temperature inside the sealed space 109 and transmits it to the control device 200. The pressure derivation unit 902 derives the pressure based on the temperature of the sealed space 109 and the volume of the sealed space. An example of the derivation method will be described later.

[0051] [Processing flow] Fig. 10 is a flowchart of the control process of the electric actuator 10 according to this embodiment. This process is executed by the control device 200, for example, by reading out from a storage device (not shown) and executing a program for implementing each part shown in Fig. 9.

[0052] In S1001, the control device 200 receives an operation instruction for the electric actuator 10 from the higher-level device 20. The operation instruction here may be, for example, a thrust value to be output by the electric actuator 10 or a movement amount of the output shaft 105.

[0053] In S1002, the control device 200 outputs a current for operating the motor 102 based on the operation instruction received in S1001. The current here is supplied to the motor 102 after being converted by the inverter 202 from the power source 203 based on a signal instructed by the motor braking unit 201.

[0054] In S1003, the control device 200 acquires the value of the current supplied to the motor 102 by the current sensor 206.

[0055] In S1004, the control device 200 derives the torque by the motor 102 from the current value acquired in S1003. The derivation method here is not particularly limited, but may be performed by referring to a table (not shown) that associates current with torque, or may be performed using a predefined calculation formula, for example.

[0056] In S1005, the control device 200 acquires the temperature inside the sealed space 109 by the temperature sensor 901.

[0057] In S1006, the control device 200 acquires position information accompanying the rotational operation of the motor 102 by the rotational position sensor 103.

[0058] In S1007, the control device 200 derives the volume of the sealed space 109 at that time based on the position information acquired in S1006. As described above, the rotation angle and the number of rotations of the motor 102 can be derived based on the position information acquired from the rotation position sensor 103, and this can be used to derive the extension / contraction state of the output shaft 105 (i.e., the stroke distance shown in FIG. 4). Then, as shown in FIG. 5(a), the volume is specified from the relationship between the stroke distance and the volume of the sealed space 109. Information indicating the relationship shown in FIG. 5 is specified in advance and stored in a storage unit (not shown).

[0059] In S1008, the control device 200 derives the pressure in the sealed space 109 based on the volume of the sealed space 109 derived in S1007 and the temperature acquired in S1005. The derivation method here is not particularly limited, but for example, the pressure may be derived using a table (not shown) that defines the correspondence between the temperature and volume and the pressure, or the pressure may be derived using a calculation formula defined in advance based on the Boyle-Charles law or the like.

[0060] In S1009, the control device 200 causes the thrust derivation unit 204 to derive the thrust of the output shaft 105 based on the torque derived in S1004 and the internal pressure derived in S1008. First, the thrust derivation unit 204 derives the thrust from the torque derived in S1004. Here, the thrust may be derived by referring to a table (not shown) in which the torque and the thrust correspond to each other, or may be derived using a predefined calculation formula. Next, the thrust derivation unit 204 derives a change amount for the thrust from the internal pressure derived in S1008 based on the relationship as described in FIG. 6 and FIG. 7. Then, the thrust derivation unit 204 derives the thrust by the output shaft 105 by combining the thrust based on the torque and the change amount. Then, this processing flow ends.

[0061] Thereafter, if a difference occurs between the thrust based on the operation command and the thrust output due to the influence of a change in the internal pressure, the torque of the motor 102 is adjusted to offset the difference. This feedback function controls the thrust based on the operation command to be equal to the thrust actually output, regardless of the change in the internal pressure of the sealed space. In other words, even if a load that inhibits the operation of the electric actuator 10 occurs due to the provision of the sealed space, it is possible to reduce the influence and output the thrust based on the operation command.

[0062] As described above, according to this embodiment, even when a temperature sensor is used instead of a pressure sensor, it is possible to output an electric actuator that suppresses the effects of load due to internal pressure by taking into account internal pressure changes that occur with the operation of the electric actuator.

[0063] <Third embodiment> Hereinafter, a third embodiment of the present invention will be described. In the second embodiment, the temperature sensor 901 is provided inside the sealed space 109. In this embodiment, a mode in which the temperature sensor 901 is provided outside the sealed space 109 will be described. Note that a description of parts that overlap with the second embodiment will be omitted, and the description will focus on the differences.

[0064] [Device configuration] Fig. 11 is a schematic diagram showing an example of the overall configuration of the device according to this embodiment. The difference from the configuration shown in Fig. 9 is that a temperature sensor 901 is provided outside the sealed space 109. As the temperature sensor 901 is provided outside the sealed space 109, a pressure derivation unit 902 according to this embodiment takes into account the thermal conductivity of the housing 101 and the like when deriving the pressure inside the sealed space 109. The processing flow is the same as that shown in Fig. 10 in the second embodiment.

[0065] 11 shows a configuration in which the temperature sensor 901 is installed on the outer periphery of the housing 101, but the present invention is not limited to this. For example, the temperature sensor 901 may be installed on the outer periphery of the output shaft 105. Alternatively, the temperature sensor 901 may be an infrared sensor or a thermograph, and may be installed apart from the housing 101.

[0066] According to this embodiment, it is possible to output the electric actuator while suppressing the influence of the load due to the internal pressure, taking into account the internal pressure change accompanying the operation of the electric actuator, by using the temperature sensor 901 as in the second embodiment. Also, in this embodiment, it is not necessary to provide a space for installing the temperature sensor 901 around the output shaft 105, so that the degree of freedom in design can be improved.

[0067] <Other embodiments> In addition, the present invention can also be realized by supplying a program or application for realizing the functions of one or more of the above-mentioned embodiments to a system or device via a network or a storage medium, etc., and having one or more processors in a computer of the system or device read and execute the program.

[0068] Moreover, it may be realized by a circuit that realizes one or more functions (for example, an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA)).

[0069] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates mutual combinations of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the descriptions in the specification and well-known technologies, and these are included in the scope of protection sought.

[0070] As described above, the present specification discloses the following: (1) An electric actuator, Housing and A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a pressure sensor configured by the output shaft and the housing and configured to detect a pressure in a sealed space in which the connecting mechanism is disposed; A control unit for controlling the operation of the motor; a deriving unit that derives a thrust force from the output shaft based on the pressure detected by the pressure sensor and a control amount of the motor by the control unit; Equipped with. According to this configuration, it is possible to output the electric actuator while suppressing the influence of the load due to the internal pressure, taking into account the internal pressure change caused by the operation of the electric actuator. In particular, since it is possible to derive the actual thrust force that is output in response to the change in the internal pressure, it is possible to further control the electric actuator based on this derived value.

[0071] (2) The electric actuator described in (1) is characterized in that the control unit adjusts the control amount of the motor so that the thrust force generated by the output shaft based on an operation instruction is equal to the thrust force derived by the derived portion. With this configuration, even if a load that impedes the operation of the electric actuator is generated due to the provision of a sealed space, the effect of this load can be reduced and control can be made to output a thrust based on an operation command.

[0072] (3) The electric actuator according to (1) or (2), wherein the pressure in the sealed space varies in response to linear movement of the output shaft. According to this configuration, it is possible to derive the actual output of the electric actuator by taking into account the pressure change in the sealed space that accompanies the linear movement of the output shaft of the electric actuator.

[0073] (4) Housing; A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a temperature sensor configured by the output shaft and the housing and configured to detect a temperature of a sealed space in which the connecting mechanism is disposed; A control unit for controlling the operation of the motor; a derivation unit that derives a thrust force by the output shaft based on the temperature detected by the temperature sensor and a control amount of the motor by the control unit; An electric actuator comprising: According to this configuration, it is possible to output the electric actuator while suppressing the influence of the load due to the internal pressure, taking into account the internal temperature change and the pressure change due to the volume change caused by the operation of the electric actuator. In particular, since it is possible to derive the actual thrust force that is output in response to the change in the internal pressure, it is possible to further control the electric actuator based on this derived value.

[0074] (5) The control unit A pressure in the sealed space is derived based on a temperature detected by the temperature sensor and a volume of the sealed space derived from a control amount of the motor; The electric actuator according to (4) is characterized in that a thrust force from the output shaft is derived based on the pressure and a control amount of the motor by the control unit. According to this configuration, it is possible to derive the actual output of the electric actuator by taking into account the internal temperature change accompanying the operation of the electric actuator and the pressure change accompanying the volume change.

[0075] (6) The electric actuator described in (5) is characterized in that the control unit adjusts the control amount of the motor so that the thrust force generated by the output shaft based on an operation instruction is equal to the thrust force derived by the derived portion. With this configuration, even if a load that impedes the operation of the electric actuator is generated due to the provision of a sealed space, the effect of this load can be reduced and control can be made to output a thrust based on an operation command.

[0076] (7) The electric actuator according to any one of (4) to (6), wherein the temperature sensor is installed within the sealed space. According to this configuration, it is possible to directly measure the temperature inside the sealed space and to accurately derive the actual thrust of the electric actuator based on that temperature.

[0077] (8) The electric actuator according to any one of (4) to (6), wherein the temperature sensor is installed in contact with an outer periphery of the housing or the output shaft that defines the sealed space. According to this configuration, it is possible to improve the degree of freedom in designing the area around the output shaft while deriving the actual thrust force of the electric actuator.

[0078] (9) The electric actuator according to any one of (4) to (6), wherein the temperature sensor is configured to detect the temperature without contacting the housing or the output shaft that constitutes the sealed space. According to this configuration, it is possible to improve the degree of freedom in designing the area around the output shaft while deriving the actual thrust force of the electric actuator.

[0079] (10) a housing; A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a pressure sensor configured by the output shaft and the housing and detecting a pressure in a sealed space in which the connecting mechanism is disposed; A method for generating thrust of an electric actuator comprising: A thrust force by the output shaft is derived based on the pressure detected by the pressure sensor and a control amount of the motor. According to this configuration, it is possible to output the electric actuator while suppressing the influence of the load due to the internal pressure, taking into account the internal pressure change caused by the operation of the electric actuator. In particular, since it is possible to derive the actual thrust force that is output in response to the change in the internal pressure, it is possible to further control the electric actuator based on this derived value.

[0080] (11) a housing; A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a temperature sensor configured by the output shaft and the housing, and detecting a temperature of a sealed space in which the connecting mechanism is disposed; A method for generating thrust of an electric actuator comprising: A method for deriving thrust force of an electric actuator, comprising the steps of: deriving thrust force by the output shaft based on a temperature detected by the temperature sensor and a control amount of the motor. According to this configuration, it is possible to output the electric actuator while suppressing the influence of the load due to the internal pressure, taking into account the internal temperature change and the pressure change due to the volume change caused by the operation of the electric actuator. In particular, since it is possible to derive the actual thrust force that is output in response to the change in the internal pressure, it is possible to further control the electric actuator based on this derived value.

[0081] (12) a housing; A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a pressure sensor configured by the output shaft and the housing and detecting a pressure in a sealed space in which the connecting mechanism is disposed; A control device for an electric actuator comprising: A program for deriving thrust from the output shaft based on the pressure detected by the pressure sensor and the control amount of the motor. According to this configuration, it is possible to output the electric actuator while suppressing the influence of the load due to the internal pressure, taking into account the internal pressure change caused by the operation of the electric actuator. In particular, since it is possible to derive the actual thrust force output affected by the internal pressure change, it is possible to further control the electric actuator based on this derived value.

[0082] (13) Housing; A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a temperature sensor configured by the output shaft and the housing, and detecting a temperature of a sealed space in which the connecting mechanism is disposed; A control device for an electric actuator comprising: A program for deriving thrust force from the output shaft based on the temperature detected by the temperature sensor and the control amount of the motor. According to this configuration, it is possible to output the electric actuator while suppressing the influence of the load due to the internal pressure, taking into account the internal temperature change and the pressure change due to the volume change caused by the operation of the electric actuator. In particular, since it is possible to derive the actual thrust force that is output in response to the change in the internal pressure, it is possible to further control the electric actuator based on this derived value. [Explanation of symbols]

[0083] 10...Electric actuator 20...Host device 100...Drive unit 101…Housing 102...Motor 103...Rotational position sensor 104...Reducer 105...Output shaft 106...Pressure sensor 107...Connection mechanism 108...Linear motion mechanism 109...Sealed space 200...Control device 201...Motor braking section 202…Inverter 203…Power supply 204...Thrust derivation section 205...Motor angle derivation section 206...Current sensor 207…Status monitoring section 208...Status output unit 901...Temperature sensor 902...Pressure outlet section

Claims

1. Housing and A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a pressure sensor configured by the output shaft and the housing and configured to detect a pressure in a sealed space in which the connecting mechanism is disposed; A control unit for controlling the operation of the motor; a deriving unit that derives a thrust force from the output shaft based on the pressure detected by the pressure sensor and a control amount of the motor by the control unit; An electric actuator comprising:

2. 2. The electric actuator according to claim 1, wherein the control unit adjusts a control amount of the motor so that a thrust force generated by the output shaft based on an operation command is equal to a thrust force derived by the derived portion.

3. 3. The electric actuator according to claim 1, wherein the pressure in the sealed space varies in response to linear movement of the output shaft.

4. Housing and A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a temperature sensor configured by the output shaft and the housing and configured to detect a temperature of a sealed space in which the connecting mechanism is disposed; A control unit for controlling the operation of the motor; a derivation unit that derives a thrust force by the output shaft based on the temperature detected by the temperature sensor and a control amount of the motor by the control unit; An electric actuator comprising:

5. The control unit is A pressure in the sealed space is derived based on a temperature detected by the temperature sensor and a volume of the sealed space derived from a control amount of the motor; 5. The electric actuator according to claim 4, wherein a thrust force from the output shaft is derived based on the pressure and a control amount of the motor by the control unit.

6. The electric actuator according to claim 4 or 5, wherein the control unit adjusts a control amount of the motor so that a thrust force generated by the output shaft based on an operation command is equal to a thrust force derived by the derived portion.

7. The electric actuator according to any one of claims 4 to 6, wherein the temperature sensor is installed within the sealed space.

8. The electric actuator according to any one of claims 4 to 6, wherein the temperature sensor is installed in contact with an outer periphery of the housing or the output shaft that constitutes the sealed space.

9. The electric actuator according to any one of claims 4 to 6, characterized in that the temperature sensor is configured to detect the temperature without contacting the housing or the output shaft that constitutes the sealed space.

10. Housing and A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a pressure sensor configured by the output shaft and the housing and detecting a pressure in a sealed space in which the connecting mechanism is disposed; A method for generating thrust of an electric actuator comprising: A thrust deriving method for an electric actuator, comprising the steps of: deriving thrust by the output shaft based on the pressure detected by the pressure sensor and a control amount of the motor.

11. Housing and A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a temperature sensor configured by the output shaft and the housing, and detecting a temperature of a sealed space in which the connecting mechanism is disposed; A method for generating thrust of an electric actuator comprising: A method for deriving thrust force of an electric actuator, comprising the steps of: deriving thrust force by the output shaft based on a temperature detected by the temperature sensor and a control amount of the motor.

12. Housing and A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a pressure sensor configured by the output shaft and the housing and detecting a pressure in a sealed space in which the connecting mechanism is disposed; A control device for an electric actuator comprising: A program for deriving thrust from the output shaft based on the pressure detected by the pressure sensor and the control amount of the motor.

13. Housing and A motor; A screw shaft to which a rotational force from the motor is input; A connecting mechanism configured to move linearly along the screw shaft as the screw shaft rotates due to the rotational force; a hollow output shaft connected to the connecting mechanism and moving linearly together with the connecting mechanism to output a thrust; a temperature sensor configured by the output shaft and the housing, and detecting a temperature of a sealed space in which the connecting mechanism is disposed; A control device for an electric actuator comprising: A program for deriving thrust force from the output shaft based on the temperature detected by the temperature sensor and the control amount of the motor.

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