Syringe pump

Abstract

To provide a syringe pump capable of suppressing addition of a force in the direction tilted against an axial direction of a barrel on a rear end surface of a plunger rod from a pressure part of the syringe pump.SOLUTION: A syringe pump 100 includes: a pressing part 151 pressing a rear end surface of a plunger rod 230 in the direction in which the plunger rod 230 moves to a barrel 210; and a slide shaft 140 which extends in an axial direction parallel to a moving direction of the plunger rod 230 and has a first end 141 which is located at one place in the axial direction and connects the pressing part. The pressing part 151 has an opposite surface 161 facing the rear end surface of the plunger rod 230. The opposite surface 161 is provided with an angle holding part 162 for holding a contact angle against the rear end surface of the plunger rod 230 constant.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to syringe pumps. [Background technology]

[0002] A syringe pump is used to administer an accurate amount of medicinal liquid from a syringe. Japanese Patent Application Laid-Open No. 2021-176390 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2023-27907 (Patent Document 2) describe a syringe pump to which a syringe filled with a medicinal liquid is attached. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-176390 [Patent Document 2] Patent Publication No. 2023-27907 Summary of the Invention [Problem to be solved by the invention]

[0004] When a blockage occurs in a liquid delivery system including a syringe, the internal pressure of the syringe increases. If the position of the barrel shifts due to an increase in the internal pressure of the syringe, a force may act on the barrel from the plunger rod in a direction inclined relative to the axial direction of the barrel. This force may further increase the position shift of the barrel. Patent Document 2 proposes a syringe pump that can suppress the position shift of the barrel.

[0005] The inventors discovered that when a blockage occurs in the liquid delivery system, a force may act from the pressing portion of the syringe pump to the rear end face of the plunger rod in a direction inclined with respect to the axial direction of the barrel.

[0006] An object of the present disclosure is to provide a syringe pump that can suppress the application of a force from a pressing portion of the syringe pump to a rear end surface of a plunger rod in a direction oblique to the axial direction of the barrel. [Means for solving the problem]

[0007] According to the present disclosure, a syringe pump applicable to a syringe including a barrel and a plunger rod fitted inside the barrel includes a pressing part that presses a rear end surface of the plunger rod in a direction in which the plunger rod moves toward the barrel, and a slide shaft that extends in an axial direction parallel to the moving direction of the plunger rod and has a first end located on one side of the axial direction to which the pressing part is connected. The pressing part has an opposing surface that faces the rear end surface of the plunger rod, and the opposing surface is provided with an angle holding part that keeps a contact angle with the rear end surface of the plunger rod constant.

[0008] In the syringe pump, the angle maintaining portion may have a bulging portion that bulges toward the rear end surface of the plunger rod, and a tip end of the bulging portion may be in line contact with the rear end surface.

[0009] In the syringe pump, the angle maintaining portion may have a bulging portion that bulges toward the rear end surface of the plunger rod, and a tip end of the bulging portion may be in point contact with the rear end surface.

[0010] In the syringe pump, the angle maintaining portion may have a spring member that abuts against the rear end surface of the plunger rod.

[0011] In the syringe pump, the spring member may be a leaf spring including a contact portion that contacts the rear end surface of the plunger rod and a base portion that is fixed to the opposing surface. Effect of the Invention

[0012] According to the syringe pump according to the present disclosure, it is possible to suppress the generation of a force acting from the pressing portion of the syringe pump to the rear end surface of the plunger rod in a direction inclined with respect to the axial direction of the barrel. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view showing a configuration of a syringe pump according to an embodiment. [Diagram 2] FIG. 2 is a perspective view showing the appearance of a syringe attached to a syringe pump. [Diagram 3] 1 is a perspective view showing a structure of a syringe pump according to an embodiment; [Figure 4] FIG. 1 is a front view showing a structure of a syringe pump according to an embodiment. [Diagram 5] FIG. 1 is a plan view showing a structure of a syringe pump according to an embodiment. [Figure 6] FIG. 4 is a perspective view showing components that constitute the opposing surface and the angle maintaining portion. [Figure 7] 13 is a diagram showing a state in which the angle maintaining portion abuts against the rear end surface of the plunger rod. FIG. [Figure 8] FIG. 4 is a perspective view showing components that constitute the opposing surface and the angle maintaining portion. [Figure 9] 13 is a diagram showing a state in which the angle maintaining portion abuts against the rear end surface of the plunger rod. FIG. [Figure 10] FIG. 4 is a perspective view showing components that constitute the opposing surface and the angle maintaining portion. [Figure 11] 13 is a diagram showing a state in which the angle maintaining portion abuts against the rear end surface of the plunger rod. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present disclosure will be described with reference to the accompanying drawings. In the following description, the same reference numerals are used to designate corresponding components.

[0015] First, a common structure of syringe pump 100 in each embodiment of the present disclosure will be described with reference to Figures 1 to 5. As shown in Figure 1, syringe pump 100 includes a pressing portion 150, a slide shaft 140, and a cover 111. Syringe pump 100 is applied to syringe 200.

[0016] The pushing portion 150 holds the plunger rod 220 movably toward the barrel 210 of the syringe 200. The pushing portion 150 causes the plunger rod 220 to move toward the barrel 210.

[0017] The pressing portion 150 has an opposing surface 161 that faces the flange 221, and a movable claw portion 160 that holds the flange 221 by clamping it between the opposing surface 161. The movable claw portion 160 is biased in a direction approaching the opposing surface 161 by a biasing mechanism such as a spring. The opposing surface 161 is provided with an angle retaining portion 162. The angle retaining portion 162 will be described in detail later.

[0018] The pressing portion 150 further has an operating member 170 for manually adjusting the position of the pressing portion 150 itself and the position of the movable claw portion 160 in the extension direction of the plunger rod 220 when attaching or detaching the plunger rod 220. By rotating the operating member 170 in one direction, the pressing portion 150 is brought into a locked state in which manual movement of the pressing portion 150 is restricted, and the movable claw portion 160 is maintained in a state in which it is biased toward the opposing surface 161. By rotating the operating member 170 in the other direction, the pressing portion 150 is brought into an unlocked state, and the movable claw portion 160 is moved away from the opposing surface 161 against the biasing force.

[0019] The slide shaft 140 extends in an axial direction parallel to the moving direction of the plunger rod 220. The slide shaft 140 has a first end 141 located on one side of the slide shaft 140 in the axial direction and connected to the pressing portion 150, and a second end located on the other side of the slide shaft 140 in the axial direction.

[0020] 1, syringe pump 100 further includes a barrel receiving portion 112, a barrel holding portion 120, and a barrel flange pressing portion 130. Barrel 210 is placed on barrel receiving portion 112. Barrel receiving portion 112 has a concave portion that contacts a lower portion of the outer circumferential surface of barrel 210. A rear end of barrel receiving portion 112 located on the pressing portion 150 side is bent approximately perpendicular to the moving direction of plunger rod 220.

[0021] Fig. 2 is a perspective view showing the appearance of syringe 200 mounted on syringe pump 100 of the embodiment. As shown in Fig. 2, syringe 200 includes barrel 210 and plunger rod 220. Barrel 210 is formed of a transparent or translucent resin material such as polypropylene. A lubricant such as silicone oil may be applied to the inner peripheral surface of barrel 210.

[0022] The barrel 210 has a cylindrical storage portion 211. The storage portion 211 stores a liquid medicine inside. A liquid medicine inlet / outlet 212 is provided at the tip of the barrel 210. An opening is formed at the rear end of the barrel 210. A barrel flange 213 is provided around the opening at the rear end of the barrel 210. The barrel flange 213 is formed to protrude radially outward from the rear end of the barrel 210.

[0023] Plunger rod 220 is fitted inside barrel 210. A gasket portion (not shown) that contacts the inner peripheral surface of barrel 210 is provided at the tip of plunger rod 220. A flange 221 is provided at the rear end of plunger rod 220. Flange 221 constitutes the rear end surface of plunger rod 220. Plunger rod 220 has a connecting portion 222 that connects the gasket portion and flange 221.

[0024] 1 to 5 are mutually perpendicular directions. The Z direction is the axial direction of the cylindrical housing portion 211 and is the relative movement direction of the plunger rod 220 with respect to the barrel 210.

[0025] Fig. 3 is a perspective view showing the configuration of syringe pump 100 according to an embodiment. Fig. 4 is a front view showing the configuration of syringe pump 100. Fig. 5 is a plan view showing the configuration of syringe pump 100. Figs. 3 to 5 show syringe pump 100 viewed from different directions.

[0026] Syringe pump 100 shown in Figures 3 to 5 shows a state in which syringe 200 is attached. Syringe pump 100 in Figures 3 to 5 shows a state in which cover 111 shown in Figure 1 is removed.

[0027] Syringe pump 100 moves plunger rod 220 into storage portion 211, thereby causing the liquid medicine in storage portion 211 to flow out from liquid medicine inlet / outlet 212. Body portion 110 of syringe pump 100 mainly includes barrel holding portion 120, barrel flange pressing portion 130, and slide shaft 140.

[0028] The main body 110 has therein a drive unit and a control unit that controls the drive unit. The drive unit includes a motor that drives the slide shaft 140, and a reducer connected to the motor.

[0029] Barrel holding part 120 holds barrel 210 of syringe 200 attached to syringe pump 100. Barrel holding part 120 has a support 121 and a barrel clamp 122. Barrel clamp 122 is configured to be movable in the extension direction of support 121 (Y direction) and to be rotatable about the Y axis. Support 121 and barrel clamp 122 may be formed integrally. Barrel clamp 122 may be formed to be movable relative to support 121.

[0030] When mounting syringe 200 on syringe pump 100, barrel clamp 122 is pulled upward from the position shown in Figures 3 to 5 and moved away from main body 110 along the extension direction of support 121, and at that position barrel clamp 122 is rotated 90° about the Y-axis as the center of rotation. In this state, syringe 200 is placed on syringe pump 100. At this time, barrel 210 of syringe 200 is located in barrel receiver 112 shown in Figure 1.

[0031] 3 to 5, barrel clamp 122 comes into contact with the outer circumferential surface of barrel 210 of syringe 200. In this manner, barrel holding portion 120 holds barrel 210 of syringe 200.

[0032] The barrel flange pressing portion 130 abuts against the barrel flange 213 of the syringe 200 attached to the syringe pump 100. The barrel flange pressing portion 130 has a pressing surface 134 and a flange holder 132. The flange holder 132 is provided so as to be movable relative to the pressing surface 134 in the Z direction, which is the thickness direction of the barrel flange 213. The barrel flange pressing portion 130 may further have a biasing member that biases the flange holder 132 toward the pressing surface 134.

[0033] When syringe 200 is attached to syringe pump 100 , barrel flange 213 provided at the rear end of barrel 210 is clamped between flange holder 132 and pressing surface 134 .

[0034] The barrel flange 213 has a front surface 213A facing forward. The front surface 213A is the surface of the flat plate-shaped barrel flange 213 that faces the accommodation portion 211. When the barrel flange 213 is sandwiched between the flange holder 132 and the pressing surface 134, the lower part of the front surface 213A faces the pressing surface 134, and the lower part of the front surface 213A and the pressing surface 134 are in surface contact with each other.

[0035] Barrel clamp 122 has a main body portion that is supported by support posts 121 and abuts against barrel 210. Barrel clamp 122 further has a protrusion 123. Protrusion 123 has a rib-like shape protruding from the main body portion of barrel clamp 122. When syringe 200 is attached to syringe pump 100 and the main body portion of barrel clamp 122 abuts against the outer circumferential surface of barrel 210, abutment surface 124 at the tip of protrusion 123 abuts against an upper portion of front surface 213A of barrel flange 213.

[0036] The protrusion 123 has a curved shape. The protrusion 123 may have a shape that extends along the edge of the opening at the rear end of the barrel 210. Typically, the protrusion 123 may have an arc shape. The protrusion 123 may have a shape that extends along the edge of the barrel flange 213. The protrusion 123 and the abutment surface 124 are not limited to the illustrated example and may have any shape.

[0037] The abutment surface 124 and the pressing surface 134 are located on the same plane extending in the X direction and the Y direction. The abutment surface 124 and the pressing surface 134 are located on the same plane perpendicular to the thickness direction of the barrel flange 213. The abutment surface 124 and the pressing surface 134 are located on the same plane perpendicular to the moving direction of the plunger rod 220.

[0038] The opening at the rear end of the barrel 210 is located between an abutment surface 124 that abuts against the front surface 213A of the barrel flange 213 and a barrel flange pressing portion 130 that holds the barrel flange 213. The abutment surface 124 abuts against the barrel flange 213 above the opening of the barrel 210. The pressing surface 134 contacts the barrel flange 213 below the opening of the barrel 210.

[0039] One end of the slide shaft 140 is connected to the drive unit of the main body 110, and the other end is connected to the pressing unit 150. The slide shaft 140 is configured to be slidable in the axial direction (Z direction) of the slide shaft 140. The pressing unit 150 is connected to the main body 110 by the slide shaft 140.

[0040] Pressing portion 150 has an opposing surface 161 and a movable claw portion 160 that is movable in the Z direction relative to opposing surface 161. As shown in Figures 4 and 5, when syringe 200 is attached to syringe pump 100, movable claw portion 160 clamps and fixes flange 221 of plunger rod 220 of syringe 200 in the thickness direction of flange 221 (Z direction).

[0041] The pressing portion 150 slides in the axial direction (Z direction) of the slide shaft 140 by the slide shaft 140 as a result of the drive portion of the main body portion 110 driving the slide shaft 140. The axial direction of the slide shaft 140 is parallel to the axial direction of the plunger rod 220. The opposing surface 161 is a surface of the pressing portion 150 facing the front direction, and is also a surface opposing a flange 221 that constitutes the rear end surface of the plunger rod 220. When the pressing portion 150 moves toward the main body portion 110 along the Z direction, the angle retaining portion 162 provided on the opposing surface 161 presses the flange 221.

[0042] The movable claw portion 160 is connected to the operating member 170 via the pressing portion 150. The operating member 170 is configured to be rotatable relative to the pressing portion 150 around the Z axis as the center of rotation. When the operating member 170 is disposed at the position shown in Figs. 2 to 4, the movable claw portion 160 is located close to the opposing surface 161 in the Z direction.

[0043] 3, movable claw portion 160 slides along the Z direction and moves away from opposing surface 161 and angle retaining portion 162. In this state, syringe 200 is placed on syringe pump 100. At this time, flange 221 is disposed between angle retaining portion 162 and movable claw portion 160. Thereafter, by returning operation member 170 to its original position shown in FIG. 3, movable claw portion 160 moves in the Z direction and approaches angle retaining portion 162, and flange 221 is clamped between angle retaining portion 162 and movable claw portion 160.

[0044] In the syringe pump 100 described above, as shown in FIGS. 4 and 5, the barrel clamp 122 has an abutment surface 124 that abuts against the barrel flange 213. In addition to the configuration in which the barrel flange 213 is clamped by the barrel flange pressing portion 130, the barrel clamp 122 for holding the barrel 210 is also provided with a structure for supporting the barrel flange 213, and is configured to support the barrel flange 213 at multiple points. This improves the holding force of the barrel 210 when the plunger rod 220 moves into the barrel 210. Even if a blockage occurs in the liquid delivery system and the internal pressure of the syringe 200 increases, it is possible to suppress the barrel 210 from shifting in position, and therefore it is possible to avoid a problem in which the barrel 210 floats up from the syringe pump 100.

[0045] 4 and 5, the abutment surface 124 and the pressing surface 134 of the barrel flange pressing portion 130 are located on the same plane. The load acting on the barrel 210 by the plunger rod 220 when the plunger rod 220 moves into the barrel 210 can be received by both the abutment surface 124 and the pressing surface 134, so that the holding force of the barrel 210 can be reliably improved and displacement of the barrel 210 can be suppressed.

[0046] Next, the structure of the angle retaining portion 162 according to the first embodiment will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a perspective view showing the opposing surface and the parts that constitute the angle retaining portion, and Fig. 7 is a diagram showing the state in which the angle retaining portion abuts against the rear end surface of the plunger rod. Fig. 7 shows a state in which the opposing surface is not inclined (inclination 0°) and a state in which the opposing surface is inclined 3° (inclination 3°).

[0047] As shown in Fig. 6, an angle retaining portion 162 is provided on the opposing surface 161. The through hole 166 is a hole for attaching the movable claw portion 160, and the through hole 167 is a hole for attaching the first end 141 of the slide shaft 140. The movable claw portion 160 and the slide shaft 140 are omitted from Figs. 6 and 7.

[0048] Angle holding portion 162 is a bulging portion that bulges toward the rear end surface of plunger rod 220. More specifically, the surface of the bulging portion that constitutes angle holding portion 162 has a curved surface that curves so as to bulge from opposing surface 161. The bulging portion has the same cross section in the X direction (the horizontal direction along opposing surface 161).

[0049] 7, the bulge constituting the angle retaining portion 162 is in line contact with the rear end surface of the plunger rod 220. Here, line contact is not limited to contact along a strict geometric line, but also includes contact in a region having a relatively small area extending in one direction.

[0050] The central axis of plunger rod 220 and the line where flange 221 and the bulge contact each other are configured to be perpendicular to each other in a plan view. Angle retaining portion 162 presses the rear end surface of plunger rod 220 in a direction along the central axis of plunger rod 220.

[0051] 7, when the inclination of opposing surface 161 is 0°, flange 221 constituting the rear end surface of plunger rod 220 and opposing surface 161 face each other. At this time, flange 221 and the bulging portion constituting angle retaining portion 162 are in line contact. When pushing portion 150 is driven by slide shaft 140 to push flange 221 toward barrel 210, if the liquid delivery system is in a normal state with no blockage occurring, the state shown by the inclination of 0° in FIG. 7 is substantially maintained.

[0052] The bulging portion constituting angle retaining portion 162 comes into contact with flange 221 at the tip of the bulging portion, so that the pressing force from pressing portion 150 is applied to flange 221 in the direction in which plunger rod 220 slides (Z direction).

[0053] On the other hand, if a blockage occurs in the liquid delivery system, for example, when a clamp is mistakenly attached to a tube connected to syringe 200, causing the internal pressure of syringe 200 to rise, opposing surface 161 may be inclined with respect to flange 221, as shown by an inclination of 3° in Fig. 7. This occurs because pressing portion 150 is driven by slide shaft 140 connected to one end thereof (through-hole 167 in Fig. 6), and when the movement of pressing portion 150 in the direction toward barrel 210 is restricted, opposing surface 161 is inclined obliquely upward due to bending of slide shaft 140 and deformation of the joint between pressing portion 150 and slide shaft 140, etc.

[0054] Even in such a case, since a bulging portion is provided as angle retaining portion 162, the bulging portion comes into line contact with flange 221 only at its tip, and the pressing force applied from angle retaining portion 162 to flange 221 is applied in the direction in which plunger rod 220 slides (Z direction). In other words, even if opposing surface 161 is inclined with respect to flange 221, the direction of the force applied to flange 221 does not change. As a result, even if opposing surface 161 is inclined with respect to flange 221, problems such as flange 221 falling off pressing portion 150 can be avoided.

[0055] As a comparative example, a case is assumed in which the angle retaining portion 162 is not provided on the opposing surface 161 and the flange 221 is in direct contact with the opposing surface 161. In this case, when the opposing surface 161 is inclined, the force applied from the opposing surface 161 to the flange 221 does not coincide with the direction in which the plunger rod 220 slides (Z direction). A force is applied from the opposing surface 161 to the flange 221 in an obliquely upward direction. In this case, the movable claw portion 160 cannot continue to hold the flange 221, and it is considered that the flange 221 falls off from the opposing surface 161. When the flange 221 falls off from the pressing portion 150, the pressing portion 150 cannot press the plunger rod 220 any more.

[0056] In syringe pump 100 of the present embodiment, angle retaining portion 162 consisting of a bulging portion is provided, so that the direction of the force applied from pressing portion 150 to flange 221 can always be made to coincide with the direction in which plunger rod 220 slides (Z direction). This makes it possible to avoid the problem of flange 221 falling off the opposing surface as in the comparative example. As a result, pressing portion 150 can continue to press plunger rod 220 stably.

[0057] In the first embodiment, angle holding portion 162 is configured with a curved surface so that angle holding portion 162 comes into line contact with the rear end surface of plunger rod 220. Alternatively, angle holding portion 162 may be configured with a protrusion having a triangular cross section extending in the X direction so as to come into line contact.

[0058] The structure of the angle retaining part 162 according to the second embodiment will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a perspective view showing the opposing surface and the parts that constitute the angle retaining part, and Fig. 9 is a diagram showing the state in which the angle retaining part abuts against the rear end surface of the plunger rod. Fig. 9 shows a state in which the opposing surface is not inclined (inclination 0°) and a state in which the opposing surface is inclined 3° (inclination 3°).

[0059] As shown in Fig. 8, an angle retaining portion 162 is provided on the opposing surface 161. The through hole 166 is a hole for attaching the movable claw portion 160, and the through hole 167 is a hole for attaching the first end 141 of the slide shaft 140. The movable claw portion 160 and the slide shaft 140 are omitted from Figs. 8 and 9.

[0060] Angle holding portion 162 is a bulging portion that bulges toward the rear end surface of plunger rod 220. More specifically, the surface of the bulging portion that constitutes angle holding portion 162 bulges in a dome shape from opposing surface 161. In this embodiment, the bulging portion is circular in dome shape when viewed from the front, but it does not necessarily have to be circular. For example, it may be configured in a polygonal dome shape such as a square or hexagonal dome when viewed from the front. It may also be configured in an elliptical dome shape when viewed from the front.

[0061] 8 and 9, the bulging portion constituting the angle retaining portion 162 is in point contact with the flange 221. Here, point contact is not limited to contact at a strict geometric point, but also includes contact in an area having a relatively small area.

[0062] The central axis of plunger rod 220 is configured to coincide with the normal direction at the point where flange 221 and the bulge contact each other. Angle retaining portion 162 presses the rear end surface of plunger rod 220 in the direction along the central axis of plunger rod 220.

[0063] 9, when the inclination of opposing surface 161 is 0°, flange 221 constituting the rear end surface of plunger rod 220 and opposing surface 161 face each other. At this time, flange 221 and the bulging portion constituting angle retaining portion 162 are in point contact. When pressing portion 150 is driven by slide shaft 140 to press flange 221 toward barrel 210, if the liquid delivery system is in a normal state with no blockage occurring, the state shown at an inclination of 0° in FIG. 9 is substantially maintained.

[0064] The bulging portion constituting angle retaining portion 162 and flange 221 come into point contact at the tip of the bulging portion, so that the pressing force from pressing portion 150 is applied to flange 221 in the direction in which plunger rod 220 slides (Z direction).

[0065] On the other hand, even if the opposing surface 161 is inclined with respect to the flange 221 constituting the rear end surface of the plunger rod 220 as shown by an inclination of 3° in Fig. 9, since a bulge is provided as the angle retaining portion 162, the bulge contacts the flange 221 only at the point on its surface closest to the flange 221, and the pressing force applied from the angle retaining portion 162 to the flange 221 is applied in the direction in which the plunger rod 220 slides (Z direction). In other words, even if the opposing surface 161 is inclined with respect to the flange 221, the direction of the force applied to the flange 221 does not change. As a result, even if the opposing surface 161 is inclined with respect to the flange 221, problems such as the flange 221 falling off the pressing portion 150 can be avoided.

[0066] In syringe pump 100 of the present embodiment, angle retaining portion 162 consisting of a bulging portion is provided, so that the direction of the force applied from pressing portion 150 to flange 221 can always be made to coincide with the direction in which plunger rod 220 slides (Z direction). This makes it possible to avoid the problem of flange 221 falling off the opposing surface. As a result, pressing portion 150 can continue to press plunger rod 220 stably.

[0067] The structure of the angle retaining part 162 according to the third embodiment will be described with reference to Fig. 10 and Fig. 11. Fig. 10 is a perspective view showing the opposing surface and the parts that constitute the angle retaining part, and Fig. 11 is a diagram showing the state in which the angle retaining part abuts against the rear end surface of the plunger rod. Fig. 11 shows a state in which the opposing surface is not inclined (inclination 0°) and a state in which the opposing surface is inclined 3° (inclination 3°).

[0068] As shown in Fig. 10, an angle retaining portion 162 is provided on the opposing surface 161. Note that the through hole 166 is a hole for attaching the movable claw portion 160, and the through hole 167 is a hole for attaching the first end 141 of the slide shaft 140. These are omitted in Figs. 10 and 11.

[0069] Angle retaining portion 162 is a spring member that abuts against flange 221. More specifically, the spring member constituting angle retaining portion 162 is a leaf spring including a contact portion 163 that abuts against the rear end surface of plunger rod 220 and a base portion 164 that is fixed to opposing surface 161. Abutting portion 163 is composed of a flat plate. Base portion 164 is a flat plate that fits along opposing surface 161. Base portion 164 is fixed to opposing surface 161 with adhesive, screws, or the like. Abutting portion 163 and base portion 164 are connected by a connection portion 165.

[0070] The contact portion 163 and the opposing surface 161 are parallel to each other with a gap therebetween. The leaf spring constituting the spring member is formed, for example, by bending a metal plate. The leaf spring may also be formed of a resin molded product.

[0071] One side of the contact portion 163 is connected to the base portion 164 via the connection portion 165, so that the contact portion 163 can assume an inclined posture by the deformation of the connection portion 165.

[0072] As can be seen from FIGS. 10 and 11, the spring member constituting the angle retaining portion 162 is in surface contact with the flange 221.

[0073] 11, when the inclination of opposing surface 161 is 0°, flange 221 and opposing surface 161 face each other. At this time, flange 221 and abutment portion 163 constituting angle maintaining portion 162 come into contact from the front. When pressing portion 150 is driven by slide shaft 140 to press flange 221 toward barrel 210, if the liquid supply system is in a normal state with no blockage occurring, the state shown in FIG. 11 with an inclination of 0° is substantially maintained.

[0074] The bulging portion constituting angle retaining portion 162 and flange 221 come into contact from the front, so that the pressing force from pressing portion 150 is applied to flange 221 in the direction in which plunger rod 220 slides (Z direction).

[0075] On the other hand, even if the opposing surface 161 is inclined with respect to the rear end surface of the plunger rod 220 as shown by the inclination of 3° in FIG. 11, the leaf spring as the angle retaining portion 162 is provided, so that the contact portion 163 and the flange 221 contact each other from the front. More specifically, the inclination of the opposing surface 161 can be offset by the inclination of the abutting portion 163 of the leaf spring with respect to the opposing surface 161, so that the contact portion 163 and the flange 221 can contact each other from the front. As a result, the pressing force applied from the angle retaining portion 162 to the flange 221 is applied in the direction in which the plunger rod 220 slides (Z direction). That is, even if the opposing surface 161 is inclined with respect to the flange 221, the direction of the force applied to the flange 221 does not change. As a result, even if the opposing surface 161 is inclined with respect to the flange 221, it is possible to avoid problems such as the flange 221 falling off the pressing portion 150.

[0076] In syringe pump 100 of the present embodiment, angle retaining portion 162 made of a spring member is provided, so that the direction of the force applied from pressing portion 150 to flange 221 can always be made to coincide with the direction in which plunger rod 220 slides (Z direction). This makes it possible to avoid the problem of flange 221 falling off the opposing surface. As a result, pressing portion 150 can continue to press plunger rod 220 stably.

[0077] The abutting portion 163 of the leaf spring may be a member having a shape other than a flat plate. For example, it may be a curved shape. In the present embodiment, the spring member is configured as a leaf spring, but a spring other than a leaf spring may be used as long as it has a structure that can deform in response to the inclination of the opposing surface 161.

[0078] Although the embodiment has been described above, the disclosed embodiment should be considered to be illustrative in all respects and not restrictive. The scope of the disclosure is indicated by the claims, not the above description, and is intended to include the meaning equivalent to the claims and all modifications within the scope. [Explanation of symbols]

[0079] 100 syringe pump, 110 main body, 111 cover, 112 barrel receiving portion, 120 barrel holding portion, 121 support, 122 barrel clamp, 123 convex portion, 124 abutment surface, 130 barrel flange holding portion, 132 flange holder, 134 holding surface, 140 slide shaft, 141 first end, 150 pressing portion, 160 movable claw portion, 161 opposing surface, 162 angle holding portion, 163 abutment portion, 164 base portion, 165 connection portion, 166, 167 through holes, 170 operation member, 200 syringe, 210 barrel, 211 storage portion, 212 drug solution inlet / outlet, 213 barrel flange, 213A front surface, 220 plunger rod, 221 flange, 222 connection portion.

Claims

1. A syringe pump for use with a syringe including a barrel and a plunger rod fitted inside the barrel, comprising: a pressing portion that presses a rear end surface of the plunger rod in a direction in which the plunger rod moves toward the barrel; a slide shaft extending in an axial direction parallel to the moving direction of the plunger rod and having a first end located on one side of the axial direction to which the pressing portion is connected; the pressing portion has an opposing surface facing the rear end surface of the plunger rod, the opposing surface is provided with an angle maintaining portion that maintains a constant contact angle between the opposing surface and the rear end surface of the plunger rod.

2. 2. The syringe pump according to claim 1, wherein the angle maintaining portion has a bulging portion that bulges toward the rear end surface of the plunger rod, and a tip end of the bulging portion is in line contact with the rear end surface.

3. 2. The syringe pump according to claim 1, wherein the angle maintaining portion has a bulging portion that bulges toward the rear end surface of the plunger rod, and a tip end of the bulging portion is in point contact with the rear end surface.

4. The syringe pump according to claim 1 , wherein the angle maintaining portion has a spring member that abuts against the rear end surface of the plunger rod.

5. 5. The syringe pump according to claim 4, wherein the spring member is a leaf spring including a contact portion that contacts the rear end surface of the plunger rod and a base portion that is fixed to the opposing surface.

Images