Rotary valve

Abstract

Reduce the number of parts in the rotary valve. [Solution] The device comprises a motor (6), a rotor shaft (8) rotated axially by the motor (6), a housing (2) that houses the rotor shaft (8) in an internal space (18), a stator (4) fixed to the housing (2) at the tip of the rotor shaft (8), a rotor (10) held at the tip of the rotor shaft (8) and rotating together with the rotor shaft (8), a bearing (12) interposed between the inner circumferential surface of the housing (2) and the outer circumferential surface of the rotor shaft (8) to support the rotor shaft (8) and engage with the rotor shaft (8) in the axial direction, and an elastic member (14) provided in the internal space (18) of the housing (2) to bias the rotor shaft (8) toward the stator (4) via the bearing (12) while being independent of the rotation of the rotor shaft (8).

Description

Technical Field

[0001] The present invention relates to a rotary flow path switching valve (hereinafter referred to as a rotary valve) used in an analyzer such as a liquid chromatograph.

Background Art

[0002] In an analyzer such as a liquid chromatograph, a rotary valve is often used as a valve for switching the connection of the flow path. In a rotary valve, a rotor is held at the tip of a rotor shaft that is rotated by a motor, and the rotor shaft is biased toward the stator side by using the elastic force of an elastic member such as a coil spring, thereby pressing the rotor against the stator to secure surface pressure and thereby obtaining high pressure resistance performance (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In rotary valves, an elastic member that biases the rotor toward the stator typically rotates with the rotor shaft. To ensure smooth rotation of the rotor shaft, multiple bearings are often used in combination, including not only radial bearings that support the rotor shaft but also thrust bearings that support the elastic member. However, bearings themselves have complex shapes and require precision, and interference parts such as spacers are necessary, increasing the number of parts. An increase in the number of parts not only leads to increased product dimensions and manufacturing costs, but the accumulation of dimensional tolerances among the parts can worsen the positional accuracy of the rotor. If the positional accuracy of the rotor deteriorates, misalignment can occur between the rotor grooves and the stator holes, increasing dead volume, which can lead to carryover and diffusion and negatively affect the analysis results.

[0005] This invention has been made in view of the above-mentioned problems, and aims to reduce the number of parts in a rotary valve. [Means for solving the problem]

[0006] The rotary valve according to the present invention is Motor and, A rotor shaft that is rotated by the aforementioned motor, A housing that accommodates the rotor shaft in its internal space, The stator, fixed to the housing at the tip end of the rotor shaft, A rotor held at the tip of the rotor shaft and rotating together with the rotor shaft, A bearing interposed between the inner circumferential surface of the housing and the outer circumferential surface of the rotor shaft, supporting the rotor shaft and engaging with the rotor shaft in the axial direction, The housing includes an elastic member provided in the internal space of the housing so as to bias the rotor shaft toward the stator via the bearing, independently of the rotation of the rotor shaft. [Effects of the Invention]

[0007] According to the rotary valve of the present invention, a bearing interposed between the inner circumferential surface of the housing and the outer circumferential surface of the rotor shaft to support the rotor shaft is engaged with the rotor shaft in the axial direction, and an elastic member is provided to bias the rotor shaft toward the stator side via the bearing while being independent of the rotation of the rotor shaft. As a result, the elastic member does not rotate with the rotation of the rotor shaft, and a bearing to support the elastic member is unnecessary. This makes it possible to use only one bearing to achieve smooth rotation of the rotor shaft, and reduces the number of parts in the rotary valve. [Brief explanation of the drawing]

[0008] [Figure 1] This is a partial cross-sectional view showing one embodiment of a rotary valve. [Figure 2] This is a partial cross-sectional view showing the motor removed in the same embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, an embodiment of the rotary valve according to the present invention will be described with reference to the drawings.

[0010] As shown in Figure 1, the rotary valve 1 mainly comprises a housing 2, a stator 4, a motor 6, a rotor shaft 8, a rotor 10, a bearing 12, and an elastic member 14.

[0011] The housing 2 is a single, nearly hollow cylindrical component with an open tip (upper end in the diagram). The stator 4 is fixed to the tip of the housing 2 by bolts, and the motor 6 is fixed to the base end (lower end in the diagram) of the housing 2 by bolts. In other words, the stator 4 and motor 6 are fixed to a common single component (housing 2). Therefore, because the rotary valve 1 has a structure in which the stator 4 and motor 6 are fixed to the housing 2, which is a single, integrated structure, it has fewer parts and is easy to assemble.

[0012] The stator 4 is provided with multiple pipe connection points 20 for connecting pipes. However, only one pipe connection point 20 is shown in the figure. The pipe connection points 20 are connected via flow paths to the surface (bottom surface in the figure) on the internal space 18 side of the housing 2. When the rotor 10 rotates with the rotor 10 in contact with the bottom surface of the stator 4, the interconnection state of the multiple pipes connected to the stator 4 is switched.

[0013] The rotor shaft 8 is positioned in the internal space 18 of the housing 2 with its tip (upper end in the diagram) facing the stator 4 and its base (lower end in the diagram) facing the motor 6. The rotor shaft 8 is rotated axially by the motor 6. The rotor 10 is held at the tip of the rotor shaft 8 and rotates in conjunction with the rotation of the rotor shaft 8.

[0014] The bearing 12 is interposed between the outer circumferential surface of the rotor shaft 8 and the inner circumferential surface of the housing 2, supporting the rotor shaft 8 and stabilizing its rotation. In this embodiment, the bearing 12 is a ball bearing having an outer ring 22 and an inner ring 24. The outer ring 22 of the bearing 12 has an outer diameter slightly smaller than the inner diameter of the housing 2, and the inner ring 24 of the bearing 12 has an inner diameter slightly larger than the outer diameter of the rotor shaft 8. Note that the bearing 12 does not necessarily have to be a ball bearing; it may also be a sliding bearing.

[0015] A projection 16 is provided at the tip of the rotor shaft 8, projecting radially outward from the outer circumferential surface. In this embodiment, the projection 16 is formed by a C-type retaining ring attached to a groove provided on the outer circumferential surface of the rotor shaft 8. However, the present invention is not limited to this, and the projection 16 may be integral with the rotor shaft 8. When the projection 16 is formed integrally with the rotor shaft 8, it is necessary to perform a grinding process after machining the rod to form the projection 16. However, if the projection 16 is realized with a retaining ring, the rotor shaft 8 can be manufactured simply by fitting a retaining ring after grooving a pre-ground rod (a rod-shaped member before being processed into the rotor shaft 8), thereby reducing costs.

[0016] The bearing 12 is positioned closer to the base end of the rotor shaft 8 than the projection 16, and the inner ring 24 of the bearing 12 engages with the projection 16. In other words, the bearing 12 engages with the rotor shaft 8 only in the axial direction (upward in the figure) of the rotor shaft 8.

[0017] The elastic member 14 is positioned in a compressed state in the internal space 18 of the housing 2, closer to the base end of the rotor shaft 8 than the bearing 12, so as to bias the bearing 12 toward the stator 4. When the bearing 12 is biased toward the stator 4 by the elastic member 14, the rotor shaft 8, which engages with the bearing 12 by the projection 16, is also biased toward the stator 4, and the rotor 10, held at the tip of the rotor shaft 8, is pressed against the stator 4. This ensures a seal between the stator 4 and the rotor 10. In this embodiment, the rotor 10 is in direct contact with the stator 4, but the present invention is not limited to this, and another member fixed to the stator 4 may be interposed between the stator 4 and the rotor 10.

[0018] The elastic member 14 is directly in contact with the bearing 12 only at the outer ring 22. In other words, the elastic member 14 is in contact with the bearing 12 without interfering with the inner ring 22 of the bearing 12, and the elastic member 14 does not rotate as the rotor shaft 8 rotates. Therefore, a thrust bearing for supporting the elastic member 14 and rotating it smoothly is unnecessary. Thus, since the only component that interferes with the rotation of the rotor shaft 8 is the inner ring 24 of the bearing 12, members such as bearings for smoothing the rotation of components other than the rotor shaft 8 are unnecessary, contributing to a reduction in the number of parts of the rotary valve 1.

[0019] In this embodiment, the elastic member 14 is a coil spring having an outer diameter such that it contacts only the outer ring 22 of the bearing 12. However, the present invention is not limited to this, and any member that can bias the bearing 12, such as a leaf spring, can be used as the elastic member 14.

[0020] Also, the elastic member 14 does not necessarily have to be directly in contact with the outer ring 22 of the bearing 12. The elastic member 14 may be configured to bias the bearing 12 toward the stator 4 side via a member that contacts the outer ring 22 without interfering with the inner ring 24 of the bearing 12.

[0021] The above is an explanation when the bearing 12 is a ball bearing. When the bearing 12 is a sliding bearing, the bearing 12 itself does not rotate as the rotor shaft 8 rotates. Therefore, the elastic member 14 in contact with the bearing 12 also does not rotate, and similar to the case of the ball bearing, a thrust bearing for supporting the elastic member 14 and rotating it smoothly is unnecessary.

[0022] The motor 6 is fixed to the integrated housing 2 with the central axis of the drive shaft 28 of the motor 6 and the central axis of the rotor shaft 8 aligned. A fitting structure is provided at the tip of the drive shaft 28 of the motor 6 and the base end of the rotor shaft 8, and the fitting structure engages the drive shaft 28 of the motor 6 and the rotor shaft 8 only in the rotational direction. In this embodiment, the fitting structure is composed of a pin 30 attached to the tip of the drive shaft 28 of the motor 6, and a recess 26 and groove 32 provided at the base end of the rotor shaft 8. The pin 30 penetrates the drive shaft 28 in a direction perpendicular to the axial direction of the drive shaft 28 (left and right direction in the figure). The tip of the drive shaft 28 of the motor 6 is inserted into the recess 26 at the base end of the rotor shaft 8, and the pin 30 attached to the drive shaft 28 is fitted into the groove 32. The width of the groove 32 is approximately the same as the outer diameter of the pin 30. As a result, when the drive shaft 28 of the motor 6 rotates, the pin 30 presses against the inner surface of the groove 32 at the base end of the rotor shaft 8, causing the rotor shaft 8 to rotate.

[0023] The fitting structure is not limited to the one described above; any structure that engages the drive shaft 28 and the rotor shaft 8 only in the rotational direction is acceptable. For example, the tip of the drive shaft 28 of the motor 6 may be shaped like a gear, and the recess 26 of the rotor shaft 8 may be shaped to fit with the tip of the drive shaft 28. As described above, the drive shaft 28 and the rotor shaft 8 of the motor 6 are engaged only in the rotational direction by a simple fitting structure, so parts such as couplings that connect the drive shaft 28 and the rotor shaft 8 are unnecessary, contributing to a reduction in the number of parts.

[0024] Furthermore, as shown in Figure 2, this structure ensures that the drive shaft 28 and rotor shaft 8 of the motor 6 do not interfere with each other in the axial direction. If the drive shaft 28 and rotor shaft 8 of the motor 6 were fixed in the axial direction, removing the stator 4 from the housing 2 while the motor 6 is fixed to the housing 2 would cause the rotor shaft 8 to be pushed in the opposite direction to the motor 6 (upward in the figure) by the elastic force of the elastic member 14, potentially loading the drive shaft 28 and affecting the performance of the motor 6. In this embodiment, since the drive shaft 28 and rotor shaft 8 of the motor 6 do not interfere with each other in the axial direction, removing the stator 4 from the housing 2 does not load the drive shaft 28 of the motor 6.

[0025] In this embodiment, a retaining ring 34 is attached to the outer circumferential surface of the base end of the rotor shaft 8, preventing the rotor shaft 8 from flying out the opposite side of the motor 6 due to the elastic force of the elastic member 14 when the stator 4 is removed from the housing 2.

[0026] A rotation sensor 38 for detecting the rotational position of the drive shaft 28 of the motor 6 is mounted on the housing 2 via a mounting plate 36. This eliminates the need to provide a separate mechanism for detecting the rotational position of the drive shaft 28 of the motor 6, thereby contributing to a reduction in the number of parts.

[0027] The embodiments described above are merely examples of the rotary valve according to the present invention. Embodiments of the rotary valve according to the present invention are as follows.

[0028] One embodiment of the rotary valve according to the present invention is: Motor and, A rotor shaft that is rotated by the aforementioned motor, A housing that accommodates the rotor shaft in its internal space, The stator, fixed to the housing at the tip end of the rotor shaft, A rotor held at the tip of the rotor shaft and rotating together with the rotor shaft, A bearing interposed between the inner circumferential surface of the housing and the outer circumferential surface of the rotor shaft, supporting the rotor shaft and engaging with the rotor shaft in the axial direction, The housing includes an elastic member provided in the internal space of the housing so as to bias the rotor shaft toward the stator via the bearing, independently of the rotation of the rotor shaft.

[0029] In the first embodiment of the above-described embodiment, the bearing is a ball bearing having an inner ring and an outer ring, the inner ring of the ball bearing and the rotor shaft are engaged in the axial direction of the rotor shaft, and the elastic member is provided to directly contact the ball bearing only at the outer ring and bias the ball bearing toward the stator.

[0030] In the second aspect of the above embodiment, the rotor shaft has a projection at its tip that protrudes radially outward from its outer circumferential surface, and the bearing engages with the rotor shaft by contacting the projection. This second aspect can be combined with the first aspect.

[0031] In the third aspect of the above embodiment, the protrusion is a retaining ring attached to the outer circumferential surface of the rotor shaft. This third aspect can be combined with the first and / or second aspects.

[0032] In the fourth aspect of the above embodiment, the housing is a single integrated structure, and both the motor and the stator are fixed to the housing. This fourth aspect can be combined with the first, second, and / or third aspects described above.

[0033] In the fourth embodiment described above, the central axis of the drive shaft of the motor and the central axis of the rotor shaft may coincide with each other.

[0034] In the above case, the tip of the drive shaft of the motor and the base end of the rotor shaft are provided with a fitting structure that engages with each other in the rotational direction by fitting together, and the drive shaft of the motor and the rotor shaft may engage with each other only in the rotational direction by the fitting structure.

[0035] Furthermore, in the above case, the fitting structure may include a pin that penetrates the tip of the drive shaft of the motor perpendicular to the axial direction, and a groove provided at the base end of the rotor shaft into which the pin is fitted. [Explanation of symbols]

[0036] 1 Rotary valve 2 Housing 4 stata 6 motors 8 rotor shafts 10 rotors 12 bearings 14 Elastic members 16 Protrusion 18. Interior space of the housing 20 Pipe connection section 22 Outer ring of the bearing 24 Inner ring of the bearing 26 recesses 28 Drive shaft 30 pins 32 Groove 34 Retaining ring 36 Mounting plate 38 Rotation Sensor

Claims

1. Motor and, A rotor shaft that is rotated by the aforementioned motor, A housing that accommodates the rotor shaft in its internal space, The stator, fixed to the housing at the tip end of the rotor shaft, A rotor held at the tip of the rotor shaft and rotating together with the rotor shaft, A bearing interposed between the inner circumferential surface of the housing and the outer circumferential surface of the rotor shaft, supporting the rotor shaft and engaging with the rotor shaft in the axial direction, A rotary valve comprising: an elastic member provided in the internal space of the housing to bias the rotor shaft toward the stator side via the bearing, while being independent of the rotation of the rotor shaft.

2. The bearing is a ball bearing having an inner ring and an outer ring. The inner ring of the ball bearing and the rotor shaft are engaged in the axial direction of the rotor shaft. The rotary valve according to claim 1, wherein the elastic member is provided to bias the ball bearing toward the stator by making direct contact with the ball bearing only at the outer ring.

3. The rotor shaft has a projection at its tip that protrudes radially outward from its outer circumferential surface. The rotary valve according to claim 1, wherein the bearing engages with the rotor shaft by contacting the protruding portion.

4. The rotary valve according to claim 1, wherein the protruding portion is a retaining ring attached to the outer circumferential surface of the rotor shaft.

5. The aforementioned housing is a single, integrated structure. The rotary valve according to claim 1, wherein both the motor and the stator are fixed to the housing.

6. The rotary valve according to claim 5, wherein the central axis of the drive shaft of the motor and the central axis of the rotor shaft coincide with each other.

7. The tip of the drive shaft of the motor and the base end of the rotor shaft are provided with a fitting structure that engages with each other in the rotational direction by fitting together. The rotary valve according to claim 6, wherein the drive shaft and rotor shaft of the motor are engaged with each other only in the rotational direction by the fitting structure.

8. The rotary valve according to claim 7, wherein the fitting structure includes a pin that penetrates the tip of the drive shaft of the motor perpendicular to the axial direction, and a groove provided at the base end of the rotor shaft into which the pin is fitted.

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