Linear actuators for chromatography

Abstract

A rod-type linear actuator for use with a housing associated with a rotatable hollow, internally threaded shaft and a piston-driven device where fine, precise movement is required is provided, the actuator including a body, a lead screw engaging the rotatable hollow, internally threaded shaft and terminating in a piston, and an anti-rotation device extending from the lead screw and engaging the body or a second, opposing body.

Description

Technical Field

[0001] (Cross - reference to Related Applications) This application claims the benefit of U.S. Provisional Application No. 63 / 393,351, filed on July 29, 2022.

Background Art

[0002] The present invention relates to a rod - type linear actuator used with a housing and a piston drive in places where precise and accurate movement is required. More particularly, the present invention relates to a rod - type linear actuator used with a motor and a piston drive that drives a hollow screw shaft in places where repetitive, equal, and accurate displacement is required.

[0003] High - performance liquid chromatography (HPLC) is generally performed using a pump, an injection valve, a column, and a detector, which are usually designed to supply particularly small - volume samples and fluids under pressure. The flow rate supplied by the pump may be very small, and accurate pump control and output are required. Such a pump may be piston - driven, and it is known that the piston needs to smoothly reciprocate with a precisely controlled displacement at a constant forward or backward speed. To achieve this movement, it is known to connect the piston to a linear actuator. The linear actuator used for this application often includes a rotating element such as a lead screw, a corresponding nut, or an anti - rotation device. When using a nut, the lead screw is fixed in a predetermined position relative to the motor, and as a result, the non - rotating nut moves along the screw of the lead screw to move forward or backward. On the other hand, when using an anti - rotation device, the operation of the system is slightly different. The lead screw engages with a hollow internal screw shaft that can rotate about its axis and an anti - rotation device, and the anti - rotation device is prevented from rotating with the lead screw and is fixed relative to the lead screw, so that the lead screw moves forward or backward relative to the internally threaded shaft.

[0004] One problem was that when the anti-rotation device engaged with the lead screw adjacent to the housing rather than near the piston, the lead screw would vibrate or its position would fluctuate at the far end where the piston-driven pump is located. The piston would then have to overcome these intermittent constraints, resulting in friction and wear, and a decrease in the precision of the piston's movement.

[0005] Therefore, it is desirable to provide a rod-type linear actuator used in a housing and piston-driven device associated with an axially rotatable hollow internal screw shaft, comprising a body, a lead screw that engages with the axially rotatable hollow internal screw shaft and terminates at the piston, and an anti-rotation device extending from the lead screw and engaging with either the body or an opposing second body, thereby reducing the possibility of piston position fluctuations and deviations in speed and position. [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention satisfies the above needs and overcomes one or more problems of the prior art. [Means for solving the problem]

[0007] To solve these problems, a rod-type actuator is disclosed, which is used in combination with a piston-driven device to provide displacement, comprising a housing including a rotatable hollow internal screw shaft and a motor that drives it. The rod-type actuator includes a body, a lead screw, a rotation prevention device, and a piston. The body has a rear surface and, opposite to it, an external front surface, and is configured to connect to the housing at the rear surface and to connect to the piston-driven device at the external front surface. The body has a first passage that extends from the rear surface to the external front surface around the central axis of the body and terminates at the internal surface of the body, and has a first passage cross-sectional shape and a first passage length that is greater than or equal to the sum of the displacement and the length of the rotation prevention device. The body also has a second passage that extends from the external front surface to the internal surface of the body along the central axis of the body, and has a second passage length that is shorter than the displacement and a second passage cross-sectional shape that is narrower than the cross-sectional shape of the first passage. The main body also has a guide pin attached to the main body on its internal surface, extending parallel to the central axis of the main body, and having a guide pin length that is at least equal to the sum of the displacement and the length of the anti-rotation device, and shorter than the length of the first passage. The lead screw has a lead screw threaded portion terminating at the rear end of the lead screw and a lead screw body terminating at the first end of the lead screw opposite to the rear end of the lead screw, and is configured to engage with an axially rotatable hollow internal screw shaft. The lead screw threaded portion has a lead screw threaded length that is longer than the displacement. The anti-rotation device extends from the lead screw in the lead screw body, has an anti-rotation device length that is from the front to the rear of the anti-rotation device, and has a guide pin passage aligned with the guide pin. The guide pin is sized to pass through the guide pin passage, thereby allowing the anti-rotation device to slide along the guide pin. The anti-rotation device is sized to move inside the first passage. The piston extends from the lead screw at the first end of the lead screw and is sized to slide back and forth in the second passage.The piston is configured as an attachment to the piston-driven device, and has a piston length longer than the displacement, and is sized to reciprocate within the second passage.

[0008] Furthermore, to solve these problems, a rod-type actuator is disclosed that includes a housing containing a rotatable hollow internal screw shaft and a motor to drive it, and is used in conjunction with a piston-driven device to provide displacement. The rod-type actuator includes a main body, a second main body, a lead screw, an anti-rotation device, and a piston. The main body has a rear surface and an external front surface opposite it, and is configured to connect to the housing at the rear surface and to connect to the piston-driven device at the external front surface. The main body has a first passage that extends from the rear surface to the external front surface around the central axis of the main body and terminates at the internal surface of the main body, and has a first passage cross-sectional shape and a first passage length that is greater than or equal to the sum of the displacement and the length of the anti-rotation device. The main body also has a second passage that extends from the external front surface to the internal surface of the main body along the central axis of the main body, and has a second passage length that is shorter than the displacement and a second passage cross-sectional shape that is narrower than the cross-sectional shape of the first passage. The second main body is sized to be fixedly engaged with either the main body or the housing, and a guide pin is attached to the internal surface of the second main body. The guide pin is parallel to the central axis of the main body, has a guide pin cross-sectional shape, and extends toward the inner surface of the main body for a length of at least the sum of the displacement and the anti-rotation device length. The lead screw has a lead screw threaded portion terminating at the rear end of the lead screw and a lead screw body terminating at the first end of the lead screw opposite the rear end of the lead screw, and is configured to engage with an axially rotatable hollow internal screw shaft. The lead screw threaded portion has a lead screw thread length longer than the displacement. The anti-rotation device extends from the lead screw body away from the central axis of the main body, has an anti-rotation device length from the front to the rear of the anti-rotation device, and has a guide pin passage aligned with the guide pin. The guide pin passage is shaped to have a guide pin passage cross-sectional shape that allows the anti-rotation device to slide along the guide pin. The anti-rotation device has an anti-rotation device cross-sectional shape, which is sized to allow movement within the first passage.The guide pin passage cross-sectional shape is larger than the guide pin cross-sectional shape. The piston extends from the lead screw at the first end of the lead screw and is sized to slide and reciprocate in the second passage. The piston has a piston length and piston cross-sectional shape and is sized to fit in the second passage without interfering with it.

[0009] Other features, advantages, and embodiments of the present invention will become apparent to those skilled in the art from the various embodiments described below and the accompanying drawings.

[0010] The features, advantages, and objectives disclosed and described above, in addition to those briefly summarized above, can be understood by reading the following more specific descriptions with reference to the embodiments shown in the accompanying drawings. The accompanying drawings constitute part of this specification. It should be noted that the accompanying drawings merely illustrate typical preferred embodiments of the invention, and other similarly effective embodiments not shown in the drawings are also included in the invention, and the accompanying drawings do not limit the scope of the invention. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 shows a rod-type linear actuator in which the anti-rotation device engages with a fixed guide pin extending from the main body. [Figure 2] Figure 2 shows a rod-type linear actuator in which the anti-rotation device engages with a fixed guide pin extending from an opposing second body. [Figure 3] Figure 3 shows a hollow, internally threaded shaft that is rotatable and located at the end of a solid motor shaft. [Figure 4] Figure 4 shows a hollow, internally threaded shaft that is rotatable and connected to the gear body. [Modes for carrying out the invention]

[0012] Referring to Figure 1, a rod-type linear actuator having a displacement of 199 is shown, in which a rotation prevention device engages with a fixed guide pin extending from the main body. This rod-type actuator 100 is intended to be used in conjunction with a housing 102 and a piston-driven device 103. The housing 102 houses a motor 104, which drives a rotatable hollow internal screw shaft 106 located in the housing 102. The rotatable hollow internal screw shaft 106 may be located within the motor 104, at the end of a solid motor shaft 302 associated with the motor 104, or at the end 404 of a gear body 402 connected to the motor 104. The rotatable hollow internal screw shaft 106 located at the end of a solid motor shaft 302 associated with the motor 104 is shown in Figure 3. The rotatable hollow internal screw shaft 106 located at the end 404 of a gear body 402 connected to the motor 104 is also shown in Figure 4. The motor 104 may be a stepping motor or other motor that can be precisely controlled by an associated processor or control system such as a computer. The piston drive device is a pump or other device connected to the piston 136 and may be sealed to the body 108. Such a configuration provides high operational precision for the precise movement of the piston 136. The rod-type actuator 100 includes a body 108, a lead screw 134, an anti-rotation device 130, and a piston 136.

[0013] The main body 108 is located between the housing 102 and the piston driven device 103. The main body 108 has a rear surface 110 and an external front surface 112, with the rear surface 110 located opposite the external front surface 112. To maintain this position, the main body 108 may be configured to connect to the housing 102 at the rear surface 110, and may also be configured to connect to the piston driven device 103 at the external front surface 112.

[0014] The main body 108 provides an internal space through which the lead screw 134, the anti-rotation device 130, and the piston 136 move or pass during operation. The main body 108 has a first passage 114 that extends from the rear surface 110 to the outer front surface 112 of the main body, centered on the main body's central axis 116, and terminates at the inner surface 164 of the main body. The first passage 114 may have a first passage cross-sectional shape 118, which may be cylindrical or another first passage cross-sectional shape, such as forming a rectangular parallelepiped. The main body 108 further has a second passage 120 that extends from the outer front surface 112 to the inner surface 164 of the main body along the main body's central axis 116. The length of the second passage 120, the second passage length 194, is shorter than the displacement 199. The second passage 120 has a second passage cross-sectional shape 122. The first passage cross-sectional shape 118 is complementary to the second passage cross-sectional shape 122, and both may be cylindrical. Since the second passage 120 serves as a passage for the movement of the piston 136, the second passage 120 is narrower than the first passage 114. If both the first passage 114 and the second passage 120 are cylindrical in shape, the diameter of the cross-sectional shape 122 of the second passage is smaller than the diameter of the cross-sectional shape 118 of the first passage. The first passage 114 has a length 193, which is greater than or equal to the sum of the displacement 199 and the anti-rotation device length 198.

[0015] The main body 108 is equipped with a structure to prevent the rotation of the anti-rotation device 130, and a structure and space for moving the lead screw 134 and piston 136 forward and backward. The main body 108 may be equipped with a guide pin 128 fixed to the main body 108 at the main body internal surface 164 and positioned parallel to the main body central axis 116. In this configuration, by minimizing the contact area of ​​the guide pin 128, friction can be minimized, and at the same time, a close fit between the guide pin 128 and the corresponding part can be ensured.

[0016] Referring again to Figure 1, as the anti-rotation device 130, lead screw 134, and piston 136 move forward and backward within the first passage 114, they move forward and backward along or parallel to the body central axis 116, thus preventing any constraints or increased friction that would alter the movement of the piston 136. The guide pin 128, having a guide pin length 156, has a guide pin cross-sectional shape 166. The guide pin length 156 is at least equal to the sum of the displacement 199 and the anti-rotation device length 198, and is not greater than the first passage length 193, allowing the anti-rotation device 130 to move the displacement 199 along the guide pin 128.

[0017] The movement of the piston 136 is brought about by the movement of the lead screw 134 as a result of the rotation of the axially rotatable hollow internal screw shaft 106, regardless of whether the axially rotatable hollow internal screw shaft 106 is located within the motor 104, at the end of the solid motor shaft 302 associated with the motor 104, or at the end 404 of the gear body 402 connected to the motor 104. To provide rotation, movement, and displacement of the piston 136, the lead screw 134 has a lead screw threaded portion 160 terminating at a lead screw rear end 172 with a lead screw thread length 152 greater than the displacement 199 to ensure continuous engagement between the lead screw 134 and the axially rotatable hollow internal screw shaft 106 even at maximum displacement, and a lead screw body 162 terminating at a lead screw first end 170 opposite to the lead screw rear end 172. The lead screw 134 engages with the axially rotatable hollow internal screw shaft 106, and is configured such that it remains engaged with the axially rotatable hollow internal screw shaft 106 at each end of the displacement 199 due to the lead screw length 152.

[0018] The linear displacement of the lead screw 134, i.e., the linear displacement of the piston 136, is made possible by a rotation prevention device 130 that moves with the lead screw 134 to maintain the lead screw 134 along the main body central axis 116. As shown in Figure 1, the rotation prevention device 130 extends from the lead screw 134 away from the main body central axis 116 in the lead screw body 162 and has a guide pin passage 132 having a rotation prevention device length 198 that penetrates from the front part 196 to the rear part 195 of the rotation prevention device. The guide pin passage 132 has a cross-sectional shape that matches the guide pin cross-sectional shape 166, and both cross-sectional shapes can be cylindrical. The rotation prevention device 130 may be attached to the lead screw 134 or may be integrally configured with the lead screw 134. The guide pin passage 132 prevents the rotation of the rotation prevention device 130 while the axially rotatable hollow internal screw shaft 106 is rotating. The guide pin passage 132 is aligned with the guide pin 128, and the guide pin 128 is sized such that it can pass through the guide pin passage 132, which has a cylindrical shape due to the guide pin cross-sectional shape 176, as determined by the guide pin cross-sectional shape 166, thus allowing the anti-rotation device 130 to slide along the guide pin 128. The guide pin length 156 is at least equal to the sum of the displacement 199 and the anti-rotation device length 198, so that the anti-rotation device 130 can move the displacement 199 along the guide pin 128. The guide pin passage cross-sectional shape 176 is complementary to the guide pin cross-sectional shape 166 to avoid interference, and is larger than the guide pin cross-sectional shape 166, allowing the guide pin 128 and the guide pin passage 132 to provide a moving guide without creating unnecessary gaps. Thus, the anti-rotation device 130 provides stability by moving the guide pin 128 up and down as it moves forward or backward relative to the housing 102 together with the lead screw 134. The anti-rotation device 130 may include a low-friction surface, a coating, or a bearing in the guide pin passage 132.

[0019] The anti-rotation device 130 may be sized to slide within the first passage 114 to suppress vibration, and its shape reduces deflection that could cause the lead screw 134 to deviate from the central axis 116 of the main body. The anti-rotation device 130 can be cylindrical. The anti-rotation device 130 has an anti-rotation device cross-sectional shape 148 which is different in shape from the first passage cross-sectional shape 118, and in this way the anti-rotation device 130 is sized to fit within the first passage 114. The first passage 114 has the first passage cross-sectional shape 118, and the anti-rotation device 130 has the anti-rotation device cross-sectional shape 148, and the first passage cross-sectional shape 118 is complementary to and larger than the anti-rotation device cross-sectional shape 148. Therefore, the cross-sectional shape 148 of the anti-rotation device is sufficiently small compared to the cross-sectional shape 118 of the first passage to avoid interference, but its size is adjusted so that the anti-rotation device 130 can move forward and backward within the first passage 114 without creating unnecessary gaps, thus providing a movement guide.

[0020] Therefore, the guide pin passage 132 surrounds the guide pin 128 without interference due to the guide pin passage cross-sectional shape 176, and the rotation prevention device 130 moves within the first passage 114 without interference.

[0021] If necessary, a second guide pin 128b can be used on the opposite side of the main body central axis 116 from the guide pin 128, thereby improving stability and reducing displacement and vibration. When the second guide pin 128b is used, it is mounted on the main body 108 parallel to the main body central axis 116 on the internal surface 164 of the main body. The second guide pin 128b has a guide pin cross-sectional shape 166 and can have a guide pin length 156. When the second guide pin 128b is used, the anti-rotation device 130 is provided with a second guide pin passage 132b through which it passes, and the second guide pin passage 132b is aligned with the second guide pin 128b. The second guide pin 128b is sized to pass through the second guide pin passage 132b by its guide pin cross-sectional shape 166b, and the anti-rotation device 130 can slide along the second guide pin 128b without interference. The second guide pin 128b may have a second guide pin cross-sectional shape 166b when the second guide pin passage 132b has a second guide pin passage cross-sectional shape 176b. In this case, the second guide pin passage cross-sectional shape 176b is complementary to and larger than the second guide pin cross-sectional shape 166b.

[0022] By holding the lead screw 134 along the main body central axis 116, the piston 136 can drive the piston driven device 103 with minimal misalignment, minimizing friction and deviations in forward or backward speed. The piston 136 extends along the main body central axis 116 from the first end 170 of the lead screw 134, is sized to reciprocate while sliding in the second passage 120, and is configured to be an attachment to the piston driven device 103. The piston 136 may be integrally formed with the lead screw 134 or may be attached to the lead screw 134. The piston 136 has a piston length 174 greater than the displacement 199 and is always at least partially retained within the second passage 120, preventing the piston 136 from being completely withdrawn from the second passage 120. To enable the piston 136 to advance and retreat the required displacement, the piston 136 has a piston cross-sectional shape 144 different from the second passage cross-sectional shape 122 and is sized to reciprocate without interference within the second passage 120. Thereby, the piston 136 advances and retreats within the second passage 120, providing a movement guide without creating unnecessary voids. The second passage 120 has a second passage cross-sectional shape 122, the piston 136 has a piston cross-sectional shape 144, the second passage cross-sectional shape 122 is complementary to and larger than the piston cross-sectional shape 144. When the piston cross-sectional shape 144 and the second passage cross-sectional shape 122 are cylindrical, the diameter of the piston cross-sectional shape 144 is configured to be sufficiently smaller than the diameter of the second passage 120 to avoid interference.

[0023] Next, referring to FIG. 2, a rod-type linear actuator 200 is shown in which an anti-rotation device 130 engages a second main body 248 facing it. Instead of providing one or more guide pins 128 on the main body 208, it can be configured to provide one or more guide pins 228 on the second main body 248.

[0024] The main body 208 is a structure that provides the connection between the housing 102 and the piston driven device 103. The main body 208 has a main body rear surface 110 and a main body outer front surface 112, and the main body rear surface 110 is located on the opposite side of the main body outer front surface 112. To hold a predetermined position, the main body 208 is configured to be connected to the housing 102 at the main body rear surface 110, and is also configured to be connected to the piston driven device 103 at the main body outer front surface 112. The main body 208 provides an internal space through which the lead screw 134, the anti-rotation device 130, and the piston 136 move or pass during operation. The main body 208 has a first passage 114 with a first passage cross-sectional shape 118 that extends from the main body rear surface 110 towards the main body outer front surface 112 around the main body central axis 116 and terminates at the main body inner surface 164. Further, the main body 208 has a second passage 120 with a second passage cross-sectional shape 122 that extends from the main body outer front surface 112 towards the main body inner surface 164 along the main body central axis 116, and the second passage length 194 is shorter than the displacement 199. Since the second passage 120 provides a passage for the piston 136 to pass through, the second passage cross-sectional shape 122 is narrower than the first passage cross-sectional shape 118.

[0025] The second main body 248 is sized to fixedly engage with either one or both of the main body 208 and the housing 102. The second main body 248 can be cylindrical and can be housed within the first passage 114. The second main body 248 can have a shape that fits with the main body 208 and can be structured to prevent the second main body 248 from rotating relative to the main body 208. The second main body 248 can be provided with a second main body key groove 271 on the second main body outer surface 272 that is adapted to receive a key 280, and the main body 208 can be provided with a main body key groove 270 on the first passage inner surface 273 that is adapted to receive the key 280, whereby the main body 208 and the second main body 248 are held to each other by the key 280.

[0026] The second body 248 has a guide pin 228 attached to the inner surface 264 of the second body. The guide pin 228 is parallel to the central axis 116 of the body and has a guide pin cross-sectional shape 266. This guide pin 228 extends toward the inner surface 164 of the body for a length of guide pin length 156. The guide pin length 156 is at least equal to the sum of the displacement 199 and the anti-rotation device length 198. The guide pin 228 has a guide pin cross-sectional shape 266 and extends for a length of guide pin length 156. A modified anti-rotation device 130 is combined with this guide pin 228, and the anti-rotation device 130 is provided with a guide pin passage 132 through which it passes. The guide pin passage 132 is aligned with the guide pin 228 and is sized to allow the anti-rotation device 130 to slide along the guide pin 228 based on the guide pin cross-sectional shape 266 and the guide pin passage cross-sectional shape 176.

[0027] If necessary, a second guide pin 228b can be used on the opposite side of the main body central axis 116 from the guide pin 228 to improve stability and reduce displacement and shaking. Alternatively, if necessary, the second guide pin 228b can be mounted parallel to the main body central axis 116 on the second body inner surface 264 of the second body 248. The second guide pin 228b has a guide pin cross-sectional shape 266 and extends for a length of 156. A modified anti-rotation device 130 is combined with this second guide pin 228b, and a second guide pin passage 132b is provided through the anti-rotation device 130. The second guide pin passage 132b is aligned with the second guide pin 228b and is sized to allow the anti-rotation device 130 to slide along the second guide pin 228b, based on the guide pin cross-sectional shape 266 and the guide pin passage cross-sectional shape 176.

[0028] Similarly, various modifications are possible. That is, the configuration in which the main body 108 is equipped with one or more guide pins 128 can also be applied to a configuration in which the second main body 248 is equipped with one or more guide pins 228. Furthermore, the axially rotatable hollow internal screw shaft 106 can be provided in any one of the following locations: inside the motor 104, at the end of the solid motor shaft 302 associated with the motor 104, or at the end 404 of the gear body 402 connected to the motor 104. In addition, the anti-rotation device 130 can be attached to the lead screw 134, or the anti-rotation device 130 can be formed integrally with the lead screw 134. Furthermore, the guide pin passage 132 can be adjusted to a size that fits without interfering with the guide pin 128, based on the guide pin passage cross-sectional shape 176 and the guide pin cross-sectional shape 166. Furthermore, the anti-rotation device 130 can be adjusted to a size that fits without interference within the first passage 114.

[0029] The main body 108, the main body 208, the lead screw 134, the anti-rotation device 130, and the second main body 248 ensure that the piston 136 moves linearly along the main body central axis 116 and ensure that deviations that may affect the forward speed of the piston 136 are avoided.

[0030] The terms and expressions used herein are for illustrative purposes only and not for limitation. The use of these terms and expressions is not intended to exclude any substantially equivalent features or parts thereof described or illustrated.

Claims

1. A rod-type actuator having displacement, used together with a housing and a piston-driven device, Here, the housing includes a motor that drives a hollow internal screw shaft located within the housing and rotatable on an axis, The aforementioned rod-type actuator is The main unit and Here, the main body has a rear surface and an external front surface, The rear surface of the main body is located opposite to the front surface of the main body. The main body is configured to connect to the housing at the rear surface of the main body, The main body is configured to be connected to the piston driven device at the front of the main body exterior, The main body has a first passage that extends from the rear surface of the main body toward the external front surface of the main body, with respect to the central axis of the main body, and terminates on the internal surface of the main body. The first passage has a first passage cross-sectional shape, The first passage has a length equal to or greater than the sum of the displacement and the length of the anti-rotation device. The main body has a second passage along the central axis of the main body from the external front surface of the main body to the internal surface of the main body, The second passage has a second passage length that is shorter than the displacement. The second passage has a second passage cross-sectional shape, The cross-sectional shape of the second passage is narrower than the cross-sectional shape of the first passage. The main body has a guide pin, The guide pin is attached to the main body on the inner surface of the main body. The guide pin is parallel to the central axis of the main body, The aforementioned guide pin extends for a length equal to the length of the guide pin, The length of the guide pin is at least equal to the sum of the displacement and the length of the anti-rotation device, and is shorter than the length of the first passage. A lead screw having a threaded portion that terminates at the rear end of the lead screw and a lead screw body that terminates at the first end of the lead screw, Here, the rear end of the lead screw is located opposite to the first end of the lead screw. The lead screw is configured to engage with the axially rotatable hollow internal thread shaft, The lead screw thread portion has a lead screw thread length that is longer than the displacement. The lead screw body includes a rotation prevention device that extends from the lead screw so as to be separated from the central axis of the body, Here, the length of the anti-rotation device is the length from the front of the anti-rotation device to the rear of the anti-rotation device. The aforementioned anti-rotation device has a guide pin passage through it, The guide pin passage is aligned with the guide pin, The guide pin is sized to pass through the guide pin passage so that the anti-rotation device can slide along the guide pin. The anti-rotation device is of a size that allows it to move within the first passage. Piston and, Here, the piston extends from the lead screw along the central axis of the main body at the first end of the lead screw and is configured as an attachment to the piston driven device. The piston has a piston length that is longer than the displacement. The piston is sized to slide back and forth along the second passage. A rod-type actuator equipped with the following features.

2. In the rod-type actuator according to Claim 1, The main body has a second guide pin, Here, the second guide pin is attached to the main body on the inner surface of the main body, The second guide pin is parallel to the central axis of the main body, The second guide pin extends for a length equal to the length of the guide pin, The aforementioned anti-rotation device has a second guide pin passage through it, Here, the second guide pin passage is aligned with the second guide pin, The second guide pin is sized to pass through the second guide pin passage so that the anti-rotation device can slide along the second guide pin. Rod-type actuator.

3. In the rod-type actuator according to Claim 2, The rotatable hollow internal thread shaft is provided in one of the following locations: inside the motor, at the end of a solid motor shaft associated with the motor, or at the end of a gear body connected to the motor. Rod-type actuator.

4. A rod-type actuator according to claim 3, The rotation prevention device is attached to the lead screw, Rod-type actuator.

5. In the rod-type actuator according to claim 3, The rotation prevention device is formed integrally with the lead screw. Rod-type actuator.

6. In the rod-type actuator according to claim 3, The rotation prevention device has a rotation prevention device cross-sectional shape, The cross-sectional shape of the first passage is complementary to the cross-sectional shape of the anti-rotation device, and is larger than it. The cross-sectional shape of the first passage is complementary to the cross-sectional shape of the second passage. The guide pin has a guide pin cross-sectional shape, The guide pin passage has a guide pin passage cross-sectional shape, The cross-sectional shape of the guide pin passage is complementary to the cross-sectional shape of the guide pin, and is larger than it. The second guide pin has a second guide pin cross-sectional shape, The second guide pin passage has a cross-sectional shape of the second guide pin passage, The cross-sectional shape of the second guide pin passage is complementary to the cross-sectional shape of the second guide pin and is larger than it. The piston has a piston cross-sectional shape, The cross-sectional shape of the second passage is complementary to the cross-sectional shape of the piston and is larger than it. Rod-type actuator.

7. In the rod-type actuator according to claim 1, The aforementioned anti-rotation device is cylindrical in shape. Rod-type actuator.

8. A rod-type actuator having displacement, used together with a housing and a piston-driven device, Here, the housing includes a motor that drives a hollow internal screw shaft located within the housing and rotatable on an axis, The aforementioned rod-type actuator is The main unit and Here, the main body has a rear surface and an external front surface, The rear surface of the main body is located opposite to the front surface of the main body. The main body is configured to connect to the housing at the rear surface of the main body, The main body is configured to be connected to the piston driven device at the front of the main body exterior, The main body has a first passage that extends from the rear surface of the main body toward the external front surface of the main body, with respect to the central axis of the main body, and terminates on the internal surface of the main body. The first passage has a first passage cross-sectional shape, The first passage has a length equal to or greater than the sum of the displacement and the length of the anti-rotation device. The main body has a second passage along the central axis of the main body from the external front surface of the main body to the internal surface of the main body, The second passage has a second passage length that is shorter than the displacement. The second passage has a second passage cross-sectional shape, The cross-sectional shape of the second passage is narrower than the cross-sectional shape of the first passage. The second main body, Here, the second body is sized to be fixedly engaged with either the body or the housing, The second body has a guide pin, The guide pin is attached to the second body on the inner surface of the second body. The guide pin is parallel to the central axis of the main body, The guide pin has a guide pin cross-sectional shape, The guide pin extends toward the inner surface of the main body with a length equal to the length of the guide pin, The length of the guide pin is at least equal to the sum of the displacement and the length of the anti-rotation device. A lead screw having a threaded portion that terminates at the rear end of the lead screw and a lead screw body that terminates at the first end of the lead screw, Here, the rear end of the lead screw is located opposite to the first end of the lead screw. The lead screw is configured to engage with the axially rotatable hollow internal thread shaft, The lead screw thread portion has a lead screw thread length that is longer than the displacement. The lead screw body includes a rotation prevention device that extends from the lead screw so as to be separated from the central axis of the body, Here, the length of the anti-rotation device is the length from the front of the anti-rotation device to the rear of the anti-rotation device. The aforementioned anti-rotation device has a guide pin passage through it, The guide pin passage is aligned with the guide pin, The guide pin passage is adjusted to a guide pin passage cross-sectional shape that allows the anti-rotation device to slide along the guide pin. The rotation prevention device has a rotation prevention device cross-sectional shape, The anti-rotation device is sized to fit inside the first passage. The cross-sectional shape of the guide pin passage is larger than the cross-sectional shape of the guide pin. Piston and, Here, the piston extends from the lead screw along the central axis of the main body at the first end of the lead screw, is sized to slide and reciprocate in the second passage, and is configured as an attachment to the piston driven device. The piston has a piston length, The piston has a piston cross-sectional shape, The piston is sized to fit into the second passage without interfering with it. A rod-type actuator equipped with the following features.

9. In the rod-type actuator according to claim 8, The second body has a second guide pin on the opposite side of the central axis of the body from the guide pin, The second guide pin is attached to the second body on the inner surface of the second body, The second guide pin is parallel to the central axis of the main body, The second guide pin has the same cross-sectional shape as the guide pin, The second guide pin extends toward the inner surface of the main body with a length equal to the length of the guide pin, The aforementioned anti-rotation device has a second guide pin passage through it, The second guide pin passage is aligned with the second guide pin, The second guide pin passage is sized relative to the second guide pin so as to allow the anti-rotation device to slide along the second guide pin. Rod-type actuator.

10. In the rod-type actuator according to claim 9, The second body has a second body key groove on its outer surface that matches the size of the key, The main body has a main body key groove on the inner surface of the first passage that matches the size of the key. Rod-type actuator.

11. In the rod-type actuator according to claim 1, The anti-rotation device has a low-friction surface, a coating, and a bearing in the guide pin passage. Rod-type actuator.

12. In the rod-type actuator according to claim 8, The aforementioned anti-rotation device is cylindrical in shape. Rod-type actuator.

13. In the rod-type actuator according to claim 2, The second guide pin is located on the opposite side of the main body's central axis from the guide pin, Rod-type actuator.

Images