Flow path switching valve

Abstract

The purpose of the present invention is to provide a flow path switching valve capable of improving uniformity in surface pressure occurring on a stator and a rotor seal.　This flow path switching valve has a stator, a rotor seal, a shaft for applying a rotational force to the rotor seal, a plurality of disk springs disposed on the outer periphery of the shaft, and a ball bearing rotatably supporting the shaft. A first load application point being an application point of a load on the ball bearing by a first disk spring which is, among the plurality of disk springs, in contact with the ball bearing, is located radially outside of the inner peripheries of the other disk springs.

Description

Flow path switching valve

[0001] The present invention relates to a flow path switching valve suitable for use in an analytical instrument such as a liquid chromatograph.

[0002] In the summary of Patent Document 1, a switching valve is described that has a stator forming a plurality of orifices communicating with the outside, and a rotor that is in sliding contact with the stator and is rotatable, and in which a plurality of rotor grooves communicating with the orifices are formed. This switching valve urges the rotor seal surface of the rotor against the stator in a liquid-tight manner. Further, the rotor is composed of an outer rotor and an inner rotor, and the outer rotor and the inner rotor are each provided so as to be movable toward the stator side. In paragraph 0027 of Patent Document 1, it is described that a disc spring and a bearing are respectively arranged as biasing means for the outer rotor and the inner rotor. In FIG. 2 of Patent Document 1, a ball bearing is used for the bearing.

[0003] Japanese Patent Application Laid-Open No. 2012-159460

[0004] In the switching valve of Patent Document 1, a ball bearing is used for the bearing, and further, a disc spring is used to press the seal surface (rotor seal surface) of the rotor seal against the stator. The ball bearing is a thrust bearing, and this thrust bearing is composed of an upper plate, balls, and a lower plate. And the disc spring abuts on the upper plate of the thrust bearing near the outer periphery of the shaft. In this case, the load point of the disc spring on the upper plate is near the outer periphery of the shaft, while the load point of the balls on the upper plate is the location where the balls and the upper plate contact, and the load point of the disc spring and the load point of the balls do not coincide. Therefore, the upper plate on the disc spring side is deformed, and the upper plate hits the shaft, resulting in inclination or deformation of the shaft. As a result, there is a problem that a uniform surface pressure does not occur between the stator and the rotor seal. The above-described problem occurs not only in the case of a thrust bearing but also in the case of an angular bearing using balls.

[0005] The present disclosure provides a flow path switching valve capable of improving the uniformity of the surface pressure generated between the stator and the rotor seal.

[0006] To solve the above problems, the flow path switching valve of the present invention comprises a stator having a plurality of flow paths through which a medium to be press-fitted into a housing flows, a rotor seal having a switching structure for switching the plurality of flow paths by rotation, a shaft that supports the rotor seal against the press-fitting force of the medium and also applies rotational force to the rotor seal, a plurality of disc springs arranged on the outer circumference of the shaft and applying a pressing force to the rotor seal in the press-fitting direction of the medium via the shaft, and a ball bearing that rotatably supports the shaft and supports the disc springs in the press-fitting direction of the medium, wherein the first load application point of the first disc spring that contacts the ball bearing among the plurality of disc springs, which is the point of application of the load on the ball bearing, is located radially outward with respect to the inner circumference of the other disc springs.

[0007] Furthermore, in order to solve the above problems, the flow path switching valve of the present invention comprises a stator having a plurality of flow paths through which a medium to be press-fitted into a housing flows, a rotor seal having a switching structure for switching the plurality of flow paths by rotation, a shaft that supports the rotor seal against the press-fitting force of the medium and also applies rotational force to the rotor seal, a plurality of disc springs arranged on the outer circumference of the shaft and applying a pressing force to the rotor seal in the press-fitting direction of the medium via the shaft, and a ball bearing that rotatably supports the shaft and supports the disc springs in the press-fitting direction of the medium, wherein the shaft has an enlarged diameter portion provided on the side of the rotor seal, the plurality of disc springs are arranged between the ball bearing and the enlarged diameter portion, and the inner diameter of the fourth disc spring among the plurality of disc springs that is in contact with the enlarged diameter portion is smaller than the inner diameter of the other disc springs.

[0008] Furthermore, in order to solve the above problems, the flow path switching valve of the present invention comprises a stator having a plurality of flow paths through which a medium to be press-fitted into a housing flows, a rotor seal having a switching structure for switching the plurality of flow paths by rotation, a shaft that supports the rotor seal against the press-fitting force of the medium and also applies rotational force to the rotor seal, a plurality of disc springs arranged on the outer circumference of the shaft and applying a pressing force to the rotor seal in the press-fitting direction of the medium via the shaft, and a ball bearing that rotatably supports the shaft and supports the disc springs in the press-fitting direction of the medium, wherein the shaft has a resin tape on its outer circumference, and the tape is arranged in the axial direction of the shaft in at least a part of the area in which the plurality of disc springs are arranged.

[0009] According to the present invention, it is possible to provide a flow path switching valve that can improve the uniformity of surface pressure generated between the stator and the rotor seal.

[0010] Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments.

[0011] This is an overall view showing a flow path switching valve according to the first embodiment. This is a cross-sectional view of the flow path switching valve according to the first embodiment. This is a diagram of a comparative example illustrating the operation and effect of the flow path switching valve according to the first embodiment. This is a cross-sectional view of a flow path switching valve according to the second embodiment. This is a cross-sectional view of a flow path switching valve according to the third embodiment. This is a cross-sectional view showing a modified example of the flow path switching valve according to the third embodiment. This is a cross-sectional view of a flow path switching valve according to the fifth embodiment. This is a cross-sectional view of a rotor seal according to the sixth embodiment. This is a cross-sectional view of a flow path switching valve according to the seventh embodiment.

[0012] The flow path switching valve described below comprises a stator connected to piping, a rotor seal, a shaft that rotates the rotor seal, and a housing that holds the aforementioned components. The shaft is supported by disc springs or bearings. The rotor seal is pressed against the stator by the shaft, maintaining the liquid-tightness of the rotor seal flow path and the stator flow path. The rotor seal is fixed to the shaft in the rotational direction by a pin, and the flow path is switched by rotating it with a motor connected to the shaft. Flow path switching valves are installed in analytical instruments such as liquid chromatographs to switch between multiple flow paths.

[0013] The rotor seal of the flow path switching valve rotates while being pressed against the stator by the shaft, which can cause wear on the contact surface between the rotor seal and the stator. In this case, if the shaft is tilted, uneven surface pressure will be generated between the stator and the rotor seal, which may shorten the lifespan of the flow path switching valve.

[0014] Hereinafter, a suitable embodiment for carrying out the present invention will be described with reference to the drawings as appropriate. However, the present invention is not limited to the embodiments described herein, and can be combined and improved as appropriate without changing the gist of the invention. In addition, in the following description, the vertical direction may be specified, for example, as "upper plate" or "lower plate," but this vertical direction is based on the vertical direction of the diagrams used in the description and does not specify the vertical direction when the flow path switching valve is installed. Furthermore, in the following description, in the description of the second embodiment and subsequent embodiments, the same reference numerals as in the first embodiment will be used for components similar to those in the first embodiment, and redundant explanations will be omitted.

[0015] [Example 1] The first embodiment will be described. Figure 1 is an overall view showing the flow path switching valve 100 according to the first embodiment. Figure 2 is a cross-sectional view of the flow path switching valve 100 according to the first embodiment. The flow path switching valve is composed of a stator 1, a rotor seal 2, a disc spring 3, a thrust bearing 4, a shaft 5, a radial bearing 6, a push screw 7, a housing 8, a bearing 9, and a screw 10.

[0016] The stator 1 is positioned at the upper end of the housing 8 and fixed to the housing 8 by screws 10. The housing 8 contains the rotor seal 2, disc spring 3, thrust bearing 4, shaft 5, radial bearing 6, push screw 7, and bearing 9. An enlarged diameter portion (flange portion) 51 is provided at one end of the shaft 5, and the rotor seal 2 is supported by the enlarged diameter portion 51. The other end of the shaft 5 extends outside the housing 8 and is connected to a motor (not shown). The housing 8 is a housing portion that surrounds the radially outer sides of the shaft 5 and the rotor seal 2, and one end side of the shaft 5 (rotor seal 2 side) is covered by the stator 1. Therefore, the stator 1 constitutes a housing portion (part of the housing) that covers one end side of the shaft 5.

[0017] The stator 1 has multiple flow paths 1a to 1e (only 1a to 1e are shown in Figure 1). Flow paths 1a to 1e constitute flow paths through which the medium to be press-fed into the housing 8 flows, and flow paths through which the medium is discharged from the housing 8. Multiple flow paths 1a to 1e are provided in the circumferential direction of the stator 1. One end of each flow path 1a to 1e opens to the outer surface of the stator 1. The rotor seal 2 is provided with multiple flow paths 2a (only 2a are shown in Figure 2).

[0018] The flow path 2a is provided as a recess on the sealing surface 2b of the rotor seal 2. The other ends of the flow paths 1a to 1e open into the inner surface of the stator 1 so as to face the recess that constitutes the flow path 2a. As a result, in Figure 2, flow paths 1a and 1e are connected via flow path 2a. The rotor seal 2 has a switching structure that switches the flow path of the medium that is pressed into and discharged from the housing 8 by rotation. Flow path 2a is this switching structure.

[0019] The shaft 5 supports the rotor seal 2 against the pressure input of the medium and also imparts rotational force to the rotor seal 2. The shaft 5 is supported radially by a radial bearing 6 and a bearing 9. The radial bearing 6 is provided on the inner circumference of the push screw 7 and supports the shaft 5 at the other end (motor connection side) of the shaft 5. The bearing 9 supports the shaft 5 at one end (enlarged diameter portion 51 side) by sliding against the outer circumferential surface of the enlarged diameter portion 51 of the shaft 5.

[0020] The thrust bearing 4 rotatably supports the shaft 5 and also supports the disc spring 3 in the direction of press-fitting the medium. The thrust bearing 4 is a ball bearing and has a first plate 41, balls 42, and a second plate 43. The first plate 41 is a member positioned on the disc spring 3 side relative to the balls 42 in the axial direction 5d of the shaft 5. Also, in the cross-sectional view of Figure 2, the first plate 41 is positioned above the balls 42. For this reason, the first plate 41 is sometimes called the "disc spring 3 side plate" or "upper side plate". The second plate 43 is a member positioned on the opposite side of the first plate 41 (opposite disc spring 3 side) relative to the balls 42 in the axial direction 5d of the shaft 5. Also, in the cross-sectional view of Figure 2, the second plate 43 is positioned below the balls 42. For this reason, the second plate 43 is sometimes called the opposite disc spring 3 side plate (radial bearing 6 side plate) or "lower side plate". The ball 42 is held between the first plate 41 and the second plate 43.

[0021] The disc springs 3 are positioned on the outer circumference of the shaft 5 between the thrust bearing (ball bearing) 4 and the enlarged diameter portion 51 of the shaft 5, and apply a pressing force to the rotor seal 2 in the direction of press-fitting the medium via the shaft 5. For this purpose, multiple disc springs are arranged. The multiple disc springs 3 are positioned so that both end faces form tapered surfaces with the rotation axis 5x of the shaft 5 as the center line, with the inner circumferential end (inner edge) and outer circumferential end (outer edge) offset in the vertical direction. In this embodiment, six disc springs 3 are provided. The three upper disc springs (upper disc springs or rotor seal side disc springs) 31 have their inner circumferential ends offset upward relative to their outer circumferential ends. The three lower disc springs (lower disc springs or thrust bearing side disc springs) 32 have their inner circumferential ends offset downward relative to their outer circumferential ends. In this embodiment, an example in which six disc springs 3 are used is described, but the configuration is not limited to six; more or fewer than six disc springs may be used. Furthermore, the number of lower disc springs 32 and upper disc springs 31 may be the same or different.

[0022] The disc spring 3 has its lower disc spring 32 in contact with the first plate 41 of the thrust bearing 4 on the outer circumference of the shaft 5, thereby applying a load to the first plate 41. In other words, the first plate 41 is positioned to receive the load from the disc spring. In this configuration, among the multiple disc springs 3 (32), the inner diameter φa of the disc spring 32a (first disc spring) that is in contact with the thrust bearing 4 is larger than the inner diameter φb of the disc spring 32b (second disc spring) that is positioned next to the disc spring 32a on the rotor seal 2 side in the axial direction 5d (φa > φb).

[0023] As a result, the point of application of load A on the thrust bearing (ball bearing) 4 by the first disc spring 32a, which is in contact with the thrust bearing (ball bearing) 4, is located radially outward relative to the inner circumference of the other disc springs 32b and 32c. In this case, the first point of application of load is located at the point where the first disc spring 32a and the first plate 41 are in contact, and is located closer to the second point of application of load, which is the point of application of load by the balls 42 on the first plate 41, than to the inner circumference of the other disc springs 32b and 32c.

[0024] The mechanism involves a push screw 7 pushing the thrust bearing 4 towards the upper side of the paper (towards the rotor seal 2), and the spring force of the disc spring 3, which is positioned between the thrust bearing 4 and the enlarged diameter portion 51 of the shaft 5, pushes the shaft 5 upwards. As the rotor seal 2, which is in contact with the shaft 5, is pushed upwards, surface pressure is applied between the stator 1 and the rotor seal 2.

[0025] The rotor seal 2 and the shaft 5 are restricted from relative rotation by a pin (not shown), and by rotating the shaft 5, the rotor seal 2 rotates together with the enlarged diameter portion 51 of the shaft 5, thereby switching the flow path. Figure 2 shows the state in which the flow paths 1a and 1e of the stator 1 are connected by the flow path 2a of the rotor seal 2.

[0026] Next, the effects of the first embodiment will be explained with reference to Figure 3. Figure 3 is a comparative example illustrating the effects of the flow path switching valve 100 according to the first embodiment. In Figure 3, the configuration of the flow paths 1a to 1e of the stator 1 and the flow path 2a of the rotor seal 2 has been changed from the configuration in Figure 2, and a state in which the flow paths 1a and 1e of the stator 1 are not connected is depicted. In Figure 3, the inner diameter φa of the disc spring 32a that contacts the thrust bearing 4 among the multiple disc springs 3 is made the same as the inner diameter φb of the disc spring 32b that is placed next to this disc spring 32a (φa = φb), and the first plate 41 is shown to receive the load B from the disc spring 3 on the outer circumference (near the outer circumference) of the shaft 5.

[0027] In this case, consider the situation where the push screw 7 is pushed inward into the housing 8, and a load is applied to the disc spring 3. In the thrust bearing 4, the load is received by the ball 42, and the first plate 41 receives load A at the point (part) where it contacts the ball 42. On the other hand, in the disc spring 3, load B is received on the outer circumference of the shaft 5. As a result, the first plate 41 deforms, and a lateral load in the left-right direction of the paper is applied to the shaft 5, causing the shaft 5 to deform in the left-right direction of the paper. Therefore, the surface pressure applied to the sliding surface between the stator 1 and the rotor seal 2 is not uniform. For this reason, an improvement in the lifespan of the flow path switching valve cannot be expected.

[0028] In the first embodiment, as shown in Figure 2, in order to bring the point of application of load A (first load application point) and the point of application of load B (second load application point) on the first plate 41 closer together, the inner diameter φa of the disc spring 32a that contacts the first plate 41 is made larger than the inner diameter φb of the disc spring 32b that is positioned next to it on the rotor seal 2 side (φa > φb). As a result, the points of application of load A and load B on the first plate 41 are brought closer together, the deformation of the first plate 41 is suppressed, and the deformation of the shaft 5 is also suppressed, so that a uniform surface pressure can be applied to the sliding surface between the stator 1 and the rotor seal 2. As a result, the lifespan of the flow path switching valve 100 can be improved.

[0029] Furthermore, in this embodiment, the effect of improving the lifespan of the flow path switching valve 100 is maximized by minimizing the deformation of the first plate 41 by making the point of application of load A coincide with the point of application of load B. However, it is not necessary to make the point of application of load A coincide with the point of application of load B. By positioning the inner circumference of the disc spring 32a that contacts the first plate 41 radially outward from the inner circumference of the other disc springs 3, that is, by making the inner diameter φa of the disc spring 32a slightly larger than the inner diameter φb of the other disc springs 3 (φa > φb), the point of application of load A and the point of application of load B on the first plate 41 can be brought closer together, and the deformation of the first plate 41 can be suppressed.

[0030] In Figure 2, three disc springs are arranged in the upper disc spring 31 and the lower disc spring 32, but as described above, the upper disc spring 31 and the lower disc spring 32 may each be composed of four or more, or two or fewer, disc springs.

[0031] Aligning the centers of each disc spring helps to suppress the tilt of shaft 5. By applying a firm grease between each disc spring and assembling them with the outer edges aligned, the centers of each disc spring can be aligned. Applying firm grease prevents the disc springs from moving even if the assembly is tilted.

[0032] [Example 2] A second embodiment will be described with reference to Figure 4. Figure 4 is a cross-sectional view of the flow path switching valve 100 according to the second embodiment.

[0033] In the first embodiment, the inner diameter φa of the disc spring (first disc spring) 32a that contacts the thrust bearing 4 was made larger than the inner diameter φb of the disc spring (second disc spring) 32b that is positioned next to the disc spring 3a on the rotor seal 2 side. In the second embodiment, as shown in Figure 4, the inner diameters φa, φb, and φc of the disc springs 32a, 32b, and 32c were set in order from the disc spring (first disc spring) 32a that contacts the thrust bearing 4 toward the rotor seal 2 side, so that φa > φb > φc.

[0034] In other words, the inner diameter φa of the first disc spring 32a, the inner diameter φb of the second disc spring 32b, and the inner diameter φc of the third disc spring 32c, which is positioned next to the second disc spring 32b on the rotor seal 2 side, have the relationship φa > φb > φc.

[0035] The effects of the second embodiment will now be explained. When the difference in inner diameter between disc springs 32a and 32b (|φa - φb|) in the lower disc spring 32 is large, the spring action of the disc spring 32 may be reduced. Therefore, by gradually increasing the difference in inner diameter, it is possible to make the disc spring 32 function effectively as a spring.

[0036] In Figure 4, three disc springs are placed in both the upper disc spring 31 and the lower disc spring 32, but it goes without saying that more than this number would also be effective. Aligning the centers of each disc spring helps to suppress the tilt of the shaft 5. By applying a firm grease between each disc spring and assembling them with the outer edges of the disc springs aligned, the centers of each disc spring can be aligned. Applying a firm grease prevents the disc springs from moving even if the assembly is tilted.

[0037] [Example 3] The third embodiment will be described with reference to Figure 5. Figure 5 is a cross-sectional view of the flow path switching valve 100 according to the third embodiment.

[0038] The disc spring (first disc spring) 32a that contacts the thrust bearing 4 is configured to have a portion (parallel portion) Re3 that contacts the first plate 41 of the thrust bearing 4 and is parallel to the first plate 41. That is, the first disc spring 32a has a parallel portion Re3 on its inner circumference that contacts the thrust bearing (ball bearing) 4. The parallel portion Re3 contacts the first plate 41 of the thrust bearing (ball bearing) 4 from the inner circumference of the first disc spring 32a to the point where the load from the balls 42 on the first plate 41 is applied (second load application point).

[0039] In this embodiment, the parallel portion Re3 is provided from the inner circumference of the disc spring 32a to the position where the ball 42 and the first plate 41 come into contact. In this embodiment, the inner circumference of the disc spring 32a is at the same radial position as the inner circumferences of the other disc springs 32b and 32c. That is, the inner diameters φa, φb, and φc of the disc springs 32a, 32b, and 32c are such that φa = φb = φc. However, it is not necessarily required that φa = φb = φc, and for example, the parallel portion Re3 may be provided on the inner circumference of the disc spring 32a in the first or second embodiment.

[0040] Next, the effects of the third embodiment will be described. In this embodiment, the parallel portion Re3 of the disc spring 32a and the first plate 41 are in surface contact. That is, the parallel portion Re3 constitutes the surface contact region between the disc spring 32a and the first plate 41. As a result, the point of application of load A on the first plate 41 can be considered to be the center position of the parallel portion (surface contact region) Re3 in the radial direction.

[0041] In this case, the point of application of load A on the thrust bearing (ball bearing) 4 of the first disc spring 32a, which is in contact with the thrust bearing (ball bearing) 4, is located radially outward relative to the inner circumference of the other disc springs 32b and 32c. The first point of application of load is located at the point where the first disc spring 32a and the first plate 41 are in contact, and is closer to the second point of application of load, which is the point of application of the load by the balls 42 on the first plate 41, than to the inner circumference of the other disc springs 32b and 32c. This brings the point of application of load A and the point of application of load B closer together, thereby suppressing deformation of the first plate 41. Furthermore, deformation of the shaft 5 is also suppressed, and uniform surface pressure can be applied to the sliding surface between the stator 1 and the rotor seal 2.

[0042] Here, a modified example of the third embodiment will be described with reference to Figure 6. Figure 6 is a cross-sectional view showing a modified example of the flow path switching valve 100 of the third embodiment. In Figure 5, of the six disc springs 3, only the disc spring 32a that contacts the first plate 41 has a shape with a parallel portion Re3. However, the multiple disc springs 3 may include multiple disc springs having a parallel portion Re3. It goes without saying that it is also effective to make all of the lower disc springs 32, or a part of the lower disc springs 32 including disc spring 32a, have a shape with a parallel portion Re3. Figure 6 shows an example in which all of the lower disc springs 32a, 32b, and 32c have a shape with a parallel portion Re3.

[0043] Alternatively, all of the disc springs 3 may be shaped to have a parallel portion Re3. In this case, the parallel portion Re3 provided on the upper disc spring 31 is provided on the inner circumference of the upper disc spring 31 so as to be parallel to the enlarged diameter portion 51 of the shaft 5.

[0044] Also, in Fig. 5, each of the upper plate spring 31 and the lower plate spring 32 is composed of three plate springs, but it is needless to say that it is also effective if they are composed of more plates.

[0045] In Fig. 5, the parallel portion (surface contact region) Re3 is set to the position where the ball 42 and the first plate 41 contact in the radial direction. Needless to say, even if the parallel portion (surface contact region) Re3 in the radial direction is made smaller, that is, the parallel portion (surface contact region) Re3 is moved closer to the shaft 5 side, there is still an effect. Or, even if the parallel portion (surface contact region) Re3 is made larger, there is still an effect.

[0046] [Example 4] The fourth example will be described with reference to Fig. 2. In the first example, as shown in Fig. 2, the thickness T41 of the first plate 41 of the thrust bearing 4 and the thickness T43 of the second plate 43 are substantially the same. However, in the fourth example, the thickness T41 of the first plate 41 is made thicker (T41 > T43) compared to the thickness T43 of the second plate 43.

[0047] Since the plate material becomes less likely to deform with the cube of the plate thickness, by increasing the thickness T41 of the first plate 41, the effect of suppressing the bending deformation of the first plate 41 when a load is applied is improved.

[0048] [Example 5] The fifth example will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view of the flow path switching valve 100 according to the fifth example. In the fifth example, compared with the first example, among the plurality of plate springs 3, the inner diameter φ31c of the plate spring (the fourth plate spring) 31c farthest from the thrust bearing 4 is made smaller than the inner diameters φ31a and φ31b of the other plate springs 31a and 31b (φ31c < φ31a, φ31b). The plate spring 31c is the plate spring that contacts the enlarged diameter portion 51 of the shaft 5. That is, the inner diameter φ31c of the fourth plate spring 31c that contacts the enlarged diameter portion 51 among the plurality of plate springs 31a, 31b, and 31c is smaller than the inner diameters φ31b and φ31c of the other plate springs 31b and 31c.

[0049] When the plate spring 31c is displaced in the radial direction, the contact position between the plate spring 31c and the enlarged diameter portion 51 of the shaft 5 is displaced in the radial direction, causing the shaft 5 to tilt.

[0050] When the dimensional difference between the outer diameter φ5 of the shaft 5 and the inner diameter φ31c of the disc spring 31c is large, the radial displacement of the disc spring 31c becomes large. When the displacement of the disc spring 31c becomes large, the tilt of the shaft 5 increases, and the deformation of the shaft 5 increases. This embodiment is effective in reducing the radial displacement of the disc spring 31c and suppressing the increase in deformation of the shaft 5.

[0051] [Example 6] The sixth embodiment will be described with reference to Figure 8. Figure 8 is a cross-sectional view of the rotor seal 2 according to the sixth embodiment.

[0052] The rotor seal 2 has a sealing surface portion (sliding surface portion) 21 having a sealing surface (sliding surface) 2b that slides against the stator 1, a shaft-side connecting portion 22 that abuts against the enlarged diameter portion 51 of the shaft 5, and a support column 23 that connects the sealing surface portion 21 and the shaft-side connecting portion 22. The sealing surface portion 21 and the shaft-side connecting portion 22 each have a disc shape.

[0053] In the sixth embodiment, the ratio (W23 / H23) of the width (W23) and height (H23) of the support column 23 of the rotor seal 2 was set to 1 to 2. By reducing this ratio, the rigidity of the support column 23 is reduced even when the shaft 5 is tilted, thereby improving the surface pressure difference between the stator 1 and the sealing surface (sliding surface) 21 of the rotor seal 2. If the ratio (W23 / H23) of the support column 2 of the rotor seal 2 is less than 1, there is a possibility that the rotor seal 2 will suffer mechanical failure, so the above value is preferable.

[0054] [Example 7] The seventh embodiment will be described with reference to Figure 9. Figure 9 is a cross-sectional view of the flow path switching valve 100 according to the seventh embodiment. In the seventh embodiment, a resin tape 14 is attached to the outer circumference of the shaft 5 on which the disc springs 3 are arranged. That is, the shaft 5 has a resin tape 14 on its outer circumference. In this case, the tape 14 is arranged in at least a part of the area where the multiple disc springs 3 are arranged in the axial direction 5d of the shaft 5.

[0055] Generally, there is a large tolerance between the inner diameter of the disc spring 3 and the outer diameter of the shaft 5. If the disc spring 3 is positioned on either the left or right side of the paper in Figure 2, for example, the shaft 5 will be tilted, so it is desirable to position the disc spring 3 and the shaft 5 so that their respective centers overlap. The resin tape 14 is effective for initial centering and is suitable because it does not restrict the deformation of the disc spring 3.

[0056] Although the resin tape 14 is applied to the entire outer circumference of the shaft 5 on which the disc springs 3 are arranged, it is also acceptable to apply the resin tape 14 only to the outer circumference of the shaft 5 on which 4 to 6 disc springs 3 are arranged, counting from the side in contact with the thrust bearing 4. In other words, as long as the center of the disc springs 3 and the center of the shaft 5 are not misaligned, partial application of the tape 14 is not a problem.

[0057] In the embodiments described above, examples using a thrust bearing 4 were explained. However, similar problems arise when using an angular contact bearing, which has both thrust bearing and radial bearing functions and contains balls. Therefore, the present invention is also effective when an angular contact bearing is used instead of a thrust bearing 4 in each embodiment. Thus, in this invention, both thrust bearings 4 and angular contact bearings are considered, and both are referred to as ball bearings.

[0058] As explained above, in the flow path switching valve 100 according to the first, second, and third embodiments, the load point of the disc spring 3 on the first plate 41 and the load point of the ball bearing coincide or are close to each other, so deformation of the shaft is suppressed and uniform surface pressure is achieved, which makes it possible to improve the lifespan of the flow path switching valve 100.

[0059] In the fourth embodiment, the deformation of the shaft is suppressed by increasing the rigidity of the first plate 41 of the ball bearing 4, thereby suppressing the deformation of the first plate 41.

[0060] In the fifth and seventh embodiments, the tilt of the shaft 5 is suppressed and the deformation of the shaft is suppressed by suppressing the radial displacement of the disc spring 3.

[0061] In the sixth embodiment, the lifespan of the sliding surface between the stator 1 and the rotor seal 2 is extended by improving the conformability of the rotor seal 2 to the sliding surface with the stator 1, thereby improving the lifespan of the flow path switching valve 100.

[0062] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all of the above configurations. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0063] 1... Stator, 2... Rotor seal, 3... Disc spring, 4... Ball bearing (thrust bearing), 5... Shaft, 5d... Axial direction of shaft 5, 5x... Rotation axis of shaft 5, 6... Radial bearing, 7... Push screw, 8... Housing, 9... Bearing, 10... Screw, 14... Tape, 21... Seal surface of rotor seal 2, 22... Shaft side connection part of rotor seal 2, 23... Support column of rotor seal 2, 31... Disc spring (upper disc spring or rotor seal side disc spring), 31 c...Fourth disc spring, 32...Disc spring (lower disc spring or thrust bearing side disc spring), 32a...First disc spring, 32b...Second disc spring, 32c...Third disc spring, 41...First plate (upper plate), 42...Ball, 43...Second plate (lower plate), 51...Enlarged diameter section of shaft 5, H23...Height of support column, Re3...Parallel section, W23...Width of support column, φ31c...Inner diameter of fourth disc spring 31c, φa...Inner diameter of first disc spring 32a, φb...Inner diameter of second disc spring 32b, φc...Inner diameter of third disc spring 32c.

Claims

1. A flow path switching valve comprising: a stator having a plurality of flow paths through which a medium to be press-fitted into a housing flows; a rotor seal having a switching structure for switching the plurality of flow paths by rotation; a shaft that supports the rotor seal against the press-fitting force of the medium and also applies rotational force to the rotor seal; a plurality of disc springs arranged on the outer circumference of the shaft and applying a pressing force to the rotor seal in the press-fitting direction of the medium via the shaft; and a ball bearing that rotatably supports the shaft and supports the disc springs in the press-fitting direction of the medium, wherein the first load application point, which is the point of application of the load on the ball bearing of the first disc spring that is in contact with the ball bearing among the plurality of disc springs, is located radially outward with respect to the inner circumference of the other disc springs.

2. The flow path switching valve according to claim 1, wherein the first disc spring has an inner diameter greater than the inner diameter of the other disc springs.

3. The flow path switching valve according to claim 2, wherein the other disc spring is a second disc spring positioned next to the first disc spring on the rotor seal side.

4. The ball bearing according to claim 1, comprising a ball, a first plate located on the side of the disc spring relative to the ball, and a second plate located on the opposite side of the first plate relative to the ball, wherein the first load application point is located at the portion where the first disc spring and the first plate are in contact, and is located closer to the second load application point, which is the point of application of the load by the ball on the first plate, than to the inner circumference of the other disc spring, in a flow path switching valve.

5. The flow path switching valve according to claim 4, wherein the first plate is thicker than the second plate.

6. The flow path switching valve according to claim 3, wherein the inner diameter φa of the first disc spring, the inner diameter φb of the second disc spring, and the inner diameter φc of the third disc spring, which is positioned next to the second disc spring on the rotor seal side, have the relationship φa > φb > φc.

7. The flow path switching valve according to claim 1, wherein the first disc spring has a parallel portion on its inner circumference that contacts the ball bearing.

8. The ball bearing according to claim 7, wherein the ball bearing comprises a ball, a first plate located on the side of the disc spring relative to the ball, and a second plate located on the opposite side of the first plate relative to the ball, and the parallel portion is in contact with the first plate of the ball bearing from the inner circumference of the first disc spring to the second load application point, which is the point of application of the load by the ball to the first plate, and is a flow path switching valve.

9. The flow path switching valve according to claim 8, wherein the plurality of disc springs include a plurality of disc springs having the parallel portion.

10. The flow path switching valve according to claim 1, wherein the rotor seal has a sealing surface portion that slides with the stator, a shaft-side connecting portion that abuts with the shaft, and a support column that connects the sealing surface portion and the shaft-side connecting portion, and the ratio of the width W23 of the support column to the height H23 of the support column (W23 / H23) is 1 ≤ W23 / H23 ≤ 2.

11. A flow path switching valve comprising: a stator having a plurality of flow paths through which a medium to be press-fitted into a housing flows; a rotor seal having a switching structure for switching the plurality of flow paths by rotation; a shaft that supports the rotor seal against the press-fitting force of the medium and also applies rotational force to the rotor seal; a plurality of disc springs arranged on the outer circumference of the shaft and applying a pressing force to the rotor seal in the press-fitting direction of the medium via the shaft; and a ball bearing that rotatably supports the shaft and also supports the disc springs in the press-fitting direction of the medium, wherein the shaft has an enlarged diameter portion provided on the side of the rotor seal; the plurality of disc springs are arranged between the ball bearing and the enlarged diameter portion; and the inner diameter of the fourth disc spring among the plurality of disc springs that is in contact with the enlarged diameter portion is smaller than the inner diameter of the other disc springs.

12. A flow path switching valve comprising: a stator having a plurality of flow paths through which a medium to be press-fitted into a housing flows; a rotor seal having a switching structure for switching the plurality of flow paths by rotation; a shaft that supports the rotor seal against the press-fitting force of the medium and also applies rotational force to the rotor seal; a plurality of disc springs arranged on the outer circumference of the shaft and applying a pressing force to the rotor seal in the press-fitting direction of the medium via the shaft; and a ball bearing that rotatably supports the shaft and supports the disc springs in the press-fitting direction of the medium, wherein the shaft has a resin tape on its outer circumference, and the tape is arranged in the axial direction of the shaft in at least a portion of the area in which the plurality of disc springs are arranged.

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