Negative pressure generating device

Abstract

A negative pressure generation device (10) comprises: an intake flow path (20); a compressed air flow path (36) that surrounds the periphery of the intake flow path (20); an exhaust flow path (52) that is provided downstream of the intake flow path (20) and the compressed air flow path (36); and a supply flow path (14a) that supplies compressed air to the compressed air flow path (36). A first center line (B) of the supply flow path (14a) is connected to the compressed air flow path (36) in a direction that does not intersect a central axial line (C).

Description

Negative pressure generating device

[0001] The present disclosure relates to a negative pressure generating device that generates negative pressure by a jet of compressed air.

[0002] There is known a negative pressure generating device that ejects compressed air and uses the vacuum generated at this time to suck in and discharge air. For example, Japanese Patent Publication No. 2018-511733 shows an example of a negative pressure generating device. The negative pressure generating device injects compressed air from the gap between an intake passage member that sucks in air and an exhaust passage member that discharges air toward the exhaust passage member. When the injected compressed air flows toward the exhaust passage member, it draws in the air in the intake passage member toward the exhaust passage member, thereby generating negative pressure in the intake passage member. Further, from the exhaust passage member, air having a flow rate larger than the flow rate of the compressed air is discharged.

[0003] In the negative pressure generating device, the pressure (compression energy) of the compressed air supplied from the intake passage member is converted into the flow velocity (kinetic energy) in the process of flowing through the path from the supply passage to the exhaust passage. However, if turbulence occurs in the flow of the compressed air between the supply passage and the exhaust passage, energy loss occurs. As a result, problems such as a decrease in the exhaust flow rate with respect to the flow rate of the compressed air and suppression of the negative pressure in the intake passage member occur. Therefore, in the negative pressure generating device, it is required to improve the utilization efficiency of the compressed air and further improve the energy-saving performance.

[0004] The present disclosure aims to solve the above problems.

[0005] One aspect of the present disclosure includes an intake passage extending along a central axis, a compressed air passage annularly surrounding the periphery of the intake passage, an exhaust passage connected downstream of the intake passage and the compressed air passage, and a supply passage for supplying compressed air to the compressed air passage, wherein the supply passage is connected to the compressed air passage in a direction in which the extension line of the first center line of the supply passage does not intersect the central axis, and is a negative pressure generating device.

[0006] According to the present disclosure, a negative pressure generating device excellent in the utilization efficiency of compressed air is provided.

[0007] Figure 1A is a longitudinal cross-sectional view of a negative pressure generator according to the first embodiment, and Figure 1B is a cross-sectional view along the line IB-IB in Figure 1A. Figure 2A is a cross-sectional view showing the arrangement of the supply flow path of a negative pressure generator according to a comparative example at the position of the line IB-IB in Figure 1A, and Figure 2B is an explanatory diagram showing the compressed air flow of a negative pressure generator according to a comparative example. Figure 3A is a diagram showing an example of connecting a compressed air supply source to a negative pressure generator, and Figure 3B is an explanatory diagram of the position of the nozzle of the negative pressure generator. Figure 4 is a graph showing the measurement results of the efficiency of the negative pressure generator at a first position. Figure 5A is a graph showing the measurement results of the efficiency of the negative pressure generator at a second position, and Figure 5B is a graph showing the measurement results of the efficiency of the negative pressure generator at a third position. Figure 6A is a graph showing the measurement results of the efficiency of the negative pressure generator at a fourth position, and Figure 6B is a graph showing the measurement results of the efficiency of the negative pressure generator at a fifth position. Figure 7 is a block diagram showing an example of connecting a load to a negative pressure generator. Figure 8 is a graph showing the efficiency measurement results at the first position of the negative pressure generator with a load connected. Figure 9A is a graph showing the efficiency measurement results at the second position of the negative pressure generator with a load connected, and Figure 9B is a graph showing the efficiency measurement results at the third position of the negative pressure generator with a load connected. Figure 10A is a graph showing the efficiency measurement results at the fourth position of the negative pressure generator with a load connected, and Figure 10B is a graph showing the efficiency measurement results at the fifth position of the negative pressure generator with a load connected. Figure 11A is a schematic cross-sectional view of the negative pressure generator according to the second embodiment, and Figure 11B is a schematic cross-sectional view of the negative pressure generator according to the third embodiment. Figure 12 is a longitudinal cross-sectional view of the negative pressure generator according to the fourth embodiment. Figure 13 is a longitudinal cross-sectional view of the negative pressure generator according to the fifth embodiment. Figure 14A is a longitudinal cross-sectional view of the negative pressure generator according to the sixth embodiment, and Figure 14B is a perspective view of the area near the tip of the nozzle in Figure 14A. Figure 15A is a schematic diagram illustrating the negative pressure generating device according to the seventh embodiment, and Figure 15B is a diagram illustrating the spiral hole in Figure 15A. Figure 16 is a longitudinal cross-sectional view of the negative pressure generating device according to the eighth embodiment. Figure 17A is a plan view of the second flow path block in Figure 16, viewed from the downstream side in the axial direction, and Figure 17B is a cross-sectional view along the line XVIIB-XVIIB in Figure 17A. Figure 18 is a perspective view of the second flow path block in Figure 16.Figure 19 is a schematic explanatory diagram of a negative pressure generating device according to the ninth embodiment. Figure 20 is a longitudinal cross-sectional view of a negative pressure generating device according to the tenth embodiment. Figure 21 is a longitudinal cross-sectional view of a negative pressure generating device according to the embodiment of Figure 11.

[0008] In the following embodiments, examples of negative pressure generators 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10I, and 10J are provided, which generate negative pressure and airflow in a predetermined direction by supplying compressed air. These negative pressure generators 10, 10A to 10J are connected, for example, to the suction tank 64 of a dust collector (see Figure 7) and used for exhausting the suction tank 64. The negative pressure generators 10, 10A to 10J are also used as blowers, etc., to blow away dust, water droplets, etc., adhering to the surface of a workpiece using airflow. The negative pressure generators 10, 10A to 10J are operated by compressed air supplied from a factory's compressed air line, etc.

[0009] In this specification, the negative pressure generators 10 to 10J are formed in a cylindrical shape, and the line along their center is called the central axis C, and the direction along the central axis C is also called the axial direction. Upstream and downstream refer to the relative positional relationship along the axial direction. Upstream is the direction in which the negative pressure generators 10 to 10J draw in air, and downstream is the direction in which the negative pressure generators 10 to 10J exhaust air. The direction perpendicular to the central axis C is called the radial direction, and the direction along the circumference of a circle centered on the central axis C is called the circumferential direction.

[0010] (First Embodiment) As shown in Figure 1A, the negative pressure generating device 10 according to the first embodiment includes an intake passage member 12, a supply port 14, a main body 16, and an exhaust passage member 18. The intake passage member 12, the main body 16, and the exhaust passage member 18 are formed in a cylindrical shape, and the position of their central axes coincides with the central axis C of the negative pressure generating device 10.

[0011] The intake passage member 12 is located on the upstream side. An intake passage 20 is formed in the intake passage member 12 to draw air into the negative pressure generator 10. The intake passage 20 extends axially and penetrates the interior of the intake passage member 12. A first screw structure 22, a packing housing groove 26, and a fixing part 28 are formed on the outer circumference of the intake passage member 12. The first screw structure 22 is screwed into the second screw structure 30 of the main body 16. When the intake passage member 12 is rotated by the user, the intake passage member 12 is displaced axially relative to the main body 16 and the exhaust passage member 18. The displacement of the intake passage member 12 adjusts the separation distance G that defines the cross-sectional area of ​​the compressed air outlet 36a.

[0012] The packing housing groove 26 extends in an annular shape circumferentially along the outer circumference of the intake passage member 12. A packing 24 is fitted into the packing housing groove 26. The packing 24 is made of an annular O-ring or the like. The packing 24 contacts the main body 16 to prevent compressed air from leaking upstream along the gap between the intake passage member 12 and the main body 16. The fixing portion 28 is an annular groove formed on the outer circumference of the intake passage member 12 and contacts the fixing screw 32 of the main body 16. By contacting the fixing screw 32 at the fixing portion 28, the intake passage member 12's rotation and axial displacement are restricted so as to be releasable.

[0013] The intake air passage member 12 further has a nozzle 34 near its downstream end 12c, the outer circumferential surface 12a of which is spaced apart from the main body 16. In this embodiment, the outer circumferential surface 34a of the downstream portion of the nozzle 34 is formed by a conical surface. The nozzle 34 is located on the inner circumference side of the compressed air passage 36. The downstream end 12c of the intake air passage member 12 is spaced apart upstream from the exhaust air passage member 18. An outlet 36a of the compressed air passage 36 is formed between the intake air passage member 12 and the exhaust air passage member 18. The outlet 36a extends in the circumferential direction and is formed in an annular shape when viewed from the axial direction.

[0014] The main body 16 is located near the axial center of the negative pressure generating device 10 and connects the intake passage member 12 and the exhaust passage member 18. The main body 16 has a larger outer diameter than the intake passage member 12 and surrounds the outer periphery of the intake passage member 12. The main body 16 is also located upstream of the exhaust passage member 18. Although not particularly limited, the main body 16 and the exhaust passage member 18 may be formed as a single unit connected to each other, as shown in the figure.

[0015] The main body 16 has a support portion 38 and a housing chamber 40. The support portion 38 is the part that supports the intake passage member 12 and has an insertion hole 42 into which the intake passage member 12 is inserted. A second screw structure 30 is formed at a predetermined location in the insertion hole 42. A screw hole 44 extending in the radial direction is formed in the support portion 38. The radially inward end of the screw hole 44 opens into the insertion hole 42. A fixing screw 32 is inserted into the screw hole 44. The fixing screw 32 abuts against the fixing portion 28 of the intake passage member 12 and restricts the displacement of the intake passage member 12. The fixing screw 32 can be loosened by the user, and the intake passage member 12 is rotated with the fixing screw 32 loosened.

[0016] The containment chamber 40 is located downstream of the insertion hole 42. The containment chamber 40 has an inner diameter larger than the outer diameter of the intake passage member 12 and contains a portion of the intake passage member 12 on the downstream side. The inner surface 40a of the containment chamber 40 is spaced apart from the intake passage member 12. The containment chamber 40 has a body portion 46 that extends in the axial direction while maintaining a constant inner diameter, and a reduced diameter portion 48 located downstream of the body portion 46 that narrows in a conical shape toward the downstream. The inclination angle of the reduced diameter portion 48 with respect to the central axis C is formed to be approximately the same as the inclination angle of the conical surface of the nozzle 34 of the intake passage member 12. A compressed air passage 36 is formed in the gap between the inner surface 40a of the containment chamber 40 and the outer circumferential surface 12a of the intake passage member 12.

[0017] The compressed air passage 36 is formed to surround the intake passage member 12 (intake passage 20) in a cylindrical shape. In a cross-section perpendicular to the axial direction, the compressed air passage 36 is formed in an annular shape surrounding the outer circumferential surface 12a of the intake passage member 12. The compressed air passage 36 is formed in a cylindrical shape extending axially while maintaining a substantially constant diameter in the inner part of the body portion 46. Furthermore, the compressed air passage 36 is formed in a funnel shape in the inner part of the reduced-diameter portion 48, with the diameter gradually decreasing. A supply port 14 opens into and communicates with the body portion 46 of the compressed air passage 36. Note that the opening position of the supply port 14 is not limited to the body portion 46, but may also be in the reduced-diameter portion 48.

[0018] In the compressed air passage 36, the gap between the downstream outer peripheral edge 12d of the nozzle 34 of the intake passage member 12 and the reduced diameter portion 48 forms the outlet 36a. The outlet 36a is the narrowest part in the compressed air passage 36, and the effective cross-sectional area of ​​the compressed air passage 36 depends on the distance G between the inner circumferential surface 48a of the reduced diameter portion 48 and the downstream outer peripheral edge 12d. The cross-sectional area of ​​the compressed air passage 36 can be adjusted by the axial position of the intake passage member 12.

[0019] In this embodiment, the nozzle 36a extends in an annular shape over the entire circumference. Compressed air is injected from the nozzle 36a along the inner circumferential surface 48a of the reduced diameter portion 48, in an oblique downstream direction closer to the central axis C.

[0020] The supply port 14 is provided on the outer periphery of the main body 16. An air pipe (not shown) is connected to the supply port 14, and compressed air is supplied through the air pipe. The supply port 14 has a supply channel 14a through which compressed air passes. The supply channel 14a extends linearly inside the supply port 14. In this embodiment, the first center line B of the supply channel 14a is oriented in a direction parallel to a plane perpendicular to the central axis C.

[0021] As shown in Figure 1B, in a cross-section perpendicular to the axial direction, the first centerline B of the supply channel 14a of the supply port 14 is mounted in a direction that does not intersect with the central axis C. The first centerline B of the supply channel 14a is oriented in a direction different from the radial direction. Specifically, in a cross-section perpendicular to the central axis C (Figure 1B), the first centerline B of the supply channel 14a is parallel to a predetermined tangential direction of the second centerline E of the annular compressed air channel 36. The compressed air flowing through such a supply channel 14a flows spirally along the compressed air channel 36 toward the nozzle 36a.

[0022] As shown in Figure 1A, an exhaust passage member 18 is connected to the downstream side of the main body 16. The exhaust passage member 18 has an exhaust passage 52 that penetrates the exhaust passage member 18 along the central axis C. The exhaust passage 52 exhausts the air drawn in from the supply port 14 together with compressed air. The exhaust passage member 18 may have an exhaust tapered section 54 whose diameter gradually increases toward the downstream side in order to increase the flow velocity of the ejected air.

[0023] The negative pressure generating device 10 of this embodiment is configured as described above. The negative pressure generating device 10 operates as follows.

[0024] Compressed air is supplied to the negative pressure generator 10 from the supply port 14. The compressed air is introduced into the compressed air passage 36 and deflected downstream by the compressed air passage 36. In the compressed air passage 36, the pressure energy of the compressed air is converted into kinetic energy, and the flow velocity of the compressed air increases. As a result, the compressed air is ejected as a high-speed jet through the nozzle 36a. The ejected compressed air is exhausted through the exhaust passage member 18. Due to the viscosity of the air, the air in the intake passage 20 and the exhaust passage 52 is exhausted from the exhaust passage member 18 along with the compressed air. As a result, negative pressure is generated in the intake passage 20 of the supply port 14, and air is drawn in from the intake passage member 12.

[0025] In this way, the negative pressure generator 10 generates negative pressure by utilizing the flow of compressed air. Therefore, if the energy efficiency of the compressed air can be increased, the negative pressure generator 10 can generate the desired negative pressure or airflow of the desired rate with a smaller amount of compressed air.

[0026] In the comparative example negative pressure generator 60 shown in Figure 2A, the supply port 14 is mounted radially so as to face the central axis C of the negative pressure generator 60. The negative pressure generator 60 is configured similarly to the negative pressure generator 10 shown in Figures 1A and 1B, except for the connection direction of the supply port 14. In the comparative example negative pressure generator 60, compressed air is blown from the supply port 14 in the diametrical direction of the compressed air passage 36 and strikes the outer circumferential surface 12a of the intake passage member 12. As a result, as shown in Figure 2B, the compressed air flows through the compressed air passage 36 in a turbulent state, resulting in a loss of kinetic energy. Therefore, the energy efficiency of the compressed air is reduced in the comparative example negative pressure generator 60.

[0027] In contrast, in the negative pressure generator 10 of this embodiment, as shown in Figure 1B, compressed air is supplied from a direction along the flow path of the annular compressed air passage 36. The compressed air flows spirally through the inside of the compressed air passage 36, flows downstream, and is ejected from the nozzle 36a. The compressed air ejected from the nozzle 36a in Figure 1A flows in a tornado-like manner while converging toward the central axis C. As a result, turbulence in the compressed air flow is suppressed, and the kinetic energy of the compressed air jet is efficiently supplied to the air drawn in from the intake passage 20. As a result, the negative pressure generator 10 can improve the energy efficiency of the compressed air.

[0028] The following describes the results of evaluating the utilization efficiency of compressed air using the negative pressure generating device 10.

[0029] The negative pressure generator 10 shown in Figures 1A and 1B, and the negative pressure generator 60 shown in Figures 2A and 2B were evaluated. The evaluation was performed by connecting a compressed air supply source 62 to the supply port 14 of the negative pressure generators 10 and 60, as shown in Figure 3A. Subsequently, the intake flow rate of air drawn in from the intake passage member 12 was measured for each of the negative pressure generators 10 and 60 when compressed air was supplied at various pressures.

[0030] The suction flow rate was measured under the following conditions, as shown in Figure 3B, where the position of the nozzle 34 of the intake air passage member 12 was set to the first, second, third, fourth, and fifth positions. The first position is the initial position, which is the position of the nozzle 34 in the product shipment state. The second position is where the nozzle 34 is advanced further downstream, narrowing the flow path cross-sectional area of ​​the compressed air passage 36. The third position is where the nozzle 34 is advanced even further downstream than the second position, narrowing the flow path cross-sectional area of ​​the compressed air passage 36 to its narrowest point. The fourth position is where the nozzle 34 is moved further upstream than the first position, increasing the flow path cross-sectional area of ​​the compressed air passage 36 compared to the initial state. The fifth position is where the position of the nozzle 34 is moved even further upstream than the fourth position. Subsequently, the efficiency of the negative pressure generators 10 and 60 with respect to the compressed air pressure was calculated by dividing the suction flow rate by the amount of compressed air consumed.

[0031] The efficiency measurement results are shown in Figures 4 to 6B. In each figure, the dashed line represents the measurement results of the comparative example negative pressure generator 60 shown in Figure 2A, and the solid line represents the measurement results of the first embodiment negative pressure generator 10 shown in Figures 1A and 1B.

[0032] Figure 4 shows the results of the evaluation with the nozzle 34 of the intake air passage member 12 in the first position (product shipment state) as shown in Figure 3B. As shown in Figure 4, in the first position, the negative pressure generator 10 exhibited approximately the same efficiency as the negative pressure generator 60.

[0033] Figure 5A shows the measurement results when the nozzle 34 is positioned at the second position in Figure 3B, and Figure 5B shows the measurement results when the nozzle 34 is positioned at the third position in Figure 3B. As shown in Figure 5A, at the second position, the efficiency of the negative pressure generator 10 was approximately the same as that of the negative pressure generator 60. As shown in Figure 5B, at the third position, where the cross-sectional area of ​​the compressed air passage 36 is smaller, the efficiency of the negative pressure generator 10 (first embodiment) was 7 to 25% higher than that of the negative pressure generator 60 in the supply pressure range of 0.1 to 0.5 MPa.

[0034] Figure 6A shows the measurement results when the nozzle 34 is positioned at the fourth position in Figure 3B, and Figure 6B shows the measurement results when the nozzle 34 is positioned at the fifth position in Figure 3B. The cross-sectional area of ​​the compressed air passage 36 increases in the order of Figure 6A and Figure 6B. In the cases of Figure 6A and Figure 6B, the negative pressure generators 10 and 60 had approximately the same efficiency.

[0035] From the above results, as shown in Figure 5B, it was confirmed that the negative pressure generator 10 tends to have a higher suction flow rate (suction efficiency) relative to the amount of compressed air consumed when the cross-sectional area of ​​the compressed air passage 36 is narrow (third position). In particular, it was confirmed that the utilization efficiency of compressed air is increased in environments where low-pressure compressed air of 0.2 MPa or less is supplied. Therefore, the negative pressure generator 10 of this embodiment is excellent in improving the utilization efficiency of compressed air when the compressed air line of a factory is made lower pressure to save energy.

[0036] Next, as shown in Figure 7, the efficiency of each of the negative pressure generators 10 and 60 was evaluated with a load connected. In this evaluation, a suction tank 64 and a silencer 66 were connected as loads. The intake passage members 12 of the negative pressure generators 10 and 60 are configured to receive air through the suction tank 64. The suction tank 64 was connected upstream of the negative pressure generators 10 and 60, and the silencer 66 was connected downstream of the negative pressure generators 10 and 60. Subsequently, the intake flow rate of air drawn in through the intake passage members 12 was measured while compressed air was supplied to each of the negative pressure generators 10 and 60 from a compressed air supply source 62 at various pressures. The intake flow rate was measured under conditions in which the position of the nozzle 34 of the intake passage member 12 was adjusted to the first, second, third, fourth, and fifth positions, as shown in Figure 3B. Subsequently, the efficiency of the negative pressure generators 10 and 60 with respect to the compressed air pressure was calculated by dividing the suction flow rate by the amount of compressed air consumed.

[0037] The measurement results are shown in Figures 8 to 10B. In each figure, the dashed line represents the measurement results of the comparative example negative pressure generator 60 shown in Figure 2A, and the solid line represents the measurement results of the negative pressure generator 10 according to the first embodiment shown in Figures 1A and 1B. Figure 8 shows the results of evaluation with the nozzle 34 at the first position (reference position) in Figure 3B. At the first position, the efficiency of the negative pressure generator 10 was approximately the same as the efficiency of the negative pressure generator 60.

[0038] Figure 9A shows the results of evaluating nozzle 34 in the second position shown in Figure 3B, and Figure 9B shows the results of evaluating nozzle 34 in the third position shown in Figure 3B. In the second position, where the compressed air passage 36 is narrowed, as shown in Figure 9A, the efficiency of the negative pressure generator 10 was approximately 4 to 17% higher than the efficiency of the negative pressure generator 60 in the range of 0.1 to 0.5 MPa. Also, as shown in Figure 9B, in the third position, the efficiency of the negative pressure generator 10 was approximately 11 to 20% higher than the efficiency of the negative pressure generator 60. In particular, it was confirmed that the utilization efficiency of compressed air is increased in environments where low-pressure compressed air of 0.2 MPa or less is supplied.Therefore, it was confirmed that the negative pressure generator 10 of this embodiment is excellent in improving efficiency when the supply pressure of compressed air is reduced, even when a load is connected.

[0039] Figure 10A shows the results of evaluating nozzle 34 at position 4 in Figure 3B, and Figure 10B shows the results of evaluating nozzle 34 at position 5 in Figure 3B. At positions 4 and 5, the negative pressure generators 10 and 60 had approximately the same efficiency.

[0040] From these results, it was confirmed that even under conditions where a load is connected, the negative pressure generator 10 improves the efficiency of compressed air utilization when the compressed air supply pressure is relatively low and the compressed air passage 36 is narrowed.

[0041] (Second Embodiment) As shown in FIG. 11A, the negative pressure generating device 10A according to the present embodiment includes two supply ports 14 and a supply flow path 14a. The two supply ports 14 are arranged at positions 180° apart from each other in the circumferential direction. In a cross-section perpendicular to the central axis C, the first center line B (extension line) of the supply flow path 14a of each supply port 14 is parallel to a predetermined tangential direction of the annular compressed air flow path 36. The negative pressure generating device 10A of this modification can also obtain the same effects as the negative pressure generating device 10 of FIGS. 1A and 1B.

[0042] (Third Embodiment) As shown in FIG. 11B, the negative pressure generating device 10B according to the present embodiment includes three supply ports 14. The three supply ports 14 are arranged at positions separated in the circumferential direction. In each supply port 14, the first center line B of the supply flow path 14a faces a direction parallel to a predetermined tangential direction with respect to the second center line E of the annular compressed air flow path 36 in a cross-section perpendicular to the central axis C. The negative pressure generating device 10B of this modification can also obtain the same effects as the negative pressure generating device 10 of FIGS. 1A and 1B. Note that the negative pressure generating device 10B may have four or more supply ports 14. Even in this case, the first center line B of each supply flow path 14a faces a direction parallel to a predetermined tangential direction of the annular second center line E of the compressed air flow path 36 in a cross-section perpendicular to the central axis C.

[0043] (Fourth Embodiment) As shown in FIG. 12, the negative pressure generating device 10C of the present embodiment is different from the negative pressure generating device 10 described with reference to FIGS. 1A and 1B in the attachment direction of the supply port 14C. In the following description, in the configuration of the negative pressure generating device 10C, the same components as the corresponding components of the negative pressure generating device 10 are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0044] As shown in FIG. 12, the supply port 14C is attached in a direction in which the first center line B of its supply flow path 14a is inclined at a predetermined angle θ with respect to the central axis C. The first center line B of the supply flow path 14a is inclined in a direction approaching downstream as it approaches the central axis C. The supply flow path 14a is inclined such that its downstream end is located on the downstream side in the axial direction rather than the upstream end.

[0045] The supply port 14C of the present embodiment injects compressed air into the compressed air flow path 36 in the supply flow path 14a while directing the compressed air in the downstream direction. The compressed air flowing out from the supply port 14C smoothly flows while spirally flowing downstream through the gap between the outer peripheral surface 34a of the nozzle 34 forming the compressed air flow path 36 and the inner peripheral surface 48a of the reduced diameter portion 48. Therefore, the negative pressure generating device 10C of the present embodiment can more effectively improve the utilization efficiency of compressed air.

[0046] (Fifth Embodiment) As shown in FIG. 13, the negative pressure generating device 10D of the present embodiment includes a supply port 14D. The supply flow path 14a of the supply port 14D has a tapered portion 70 at the connection portion with the compressed air flow path 36. In the configuration of the negative pressure generating device 10D, the same reference numerals are given to the corresponding configurations of the negative pressure generating device 10 described with reference to FIGS. 1A and 1B, and detailed descriptions thereof are omitted.

[0047] As shown in FIG. 13, the supply flow path 14a of the supply port 14D has a tapered portion 70 near the downstream end. The tapered portion 70 is provided at the connection portion between the supply port 14D and the compressed air flow path 36. The tapered portion 70 has an inclined surface 72 whose inner diameter gradually widens as it goes inward of the negative pressure generating device 10D. The tapered portion 70 suppresses the disturbance of the flow of compressed air by gradually expanding the compressed air. Thereby, the supply port 14D suppresses the energy loss of the compressed air. Therefore, the negative pressure generating device 10D of the present embodiment can improve the utilization efficiency of compressed air.

[0048] (Sixth Embodiment) As shown in FIG. 14A, the negative pressure generating device 10E of the present embodiment includes a flow guiding member 74 that guides the flow of compressed air in a spiral shape around the central axis C in the compressed air flow path 36. In the present embodiment, the flow guiding member 74 is constituted by a spiral step portion 76 (spiral unevenness) provided on the outer peripheral portion of the nozzle 34E of the intake flow path member 12. In the negative pressure generating device 10E, the same reference numerals are given to the corresponding configurations of the negative pressure generating device 10 described with reference to FIGS. 1A and 1B, and detailed descriptions thereof are omitted.

[0049] As shown in Figure 14B, the nozzle 34E of this embodiment has a spirally formed spiral step portion 76 on the conical portion (outer surface 34a). The spiral step portion 76 is a stepped portion formed by a surface with an inclination angle different from the inclination angle of the conical surface of the outer surface 34a of the nozzle 34E, and extends spirally to the downstream end of the nozzle 34E. In the illustrated example, the inclination angle of the surface forming the spiral step portion 76 is approximately perpendicular to the axial direction, or an inclination angle closer to perpendicular to the axial direction than the conical surface of the outer surface 34a of the nozzle 34E. However, the inclination angle of the surface forming the spiral step portion 76 is not limited to this, and it may be a surface with an angle smaller with respect to the axial direction than the inclination angle of the conical surface of the outer surface 34a of the nozzle 34E.

[0050] As shown in Figure 14A, in the portion adjacent to the spiral step portion 76, a locally large portion of the cross-section of the compressed air passage 36 is formed. Because this locally large portion of the compressed air passage 36 extends in a spiral shape, the compressed air flowing through the compressed air passage 36 can be guided in a spiral manner. Such a spiral flow of compressed air can suppress turbulence of the compressed air near the nozzle 36a, efficiently transfer the kinetic energy of the compressed air to the air passing through the intake passage 20, and improve the efficiency of compressed air utilization. As described above, the negative pressure generator 10E of this embodiment can suppress energy loss of compressed air and improve the efficiency of compressed air utilization.

[0051] In this embodiment, the spiral step portion 76 may be provided on the inner surface 40a of the housing chamber 40 instead of the outer surface 34a of the nozzle 34E. Alternatively, the spiral step portion 76 may be provided on both the outer surface 34a of the nozzle 34E and the inner surface 40a of the housing chamber 40.

[0052] Furthermore, the flow guide member 74 in this embodiment is not limited to the spiral stepped portion 76, but may be composed of a spiral convex portion or a spiral flow guide plate, etc., formed to protrude from either the outer peripheral surface 34a of the nozzle 34E or the inner surface 40a of the housing chamber 40, or both.

[0053] (Seventh Embodiment) As shown in Figure 15A, the negative pressure generating device 10F of this embodiment has a first flow path block 84 attached to the compressed air flow path 36. In the configuration of the negative pressure generating device 10F, components that are the same as the corresponding components of the negative pressure generating device 10 described with reference to Figures 1A and 1B are denoted by the same reference numerals and their detailed description is omitted.

[0054] The negative pressure generating device 10F comprises an intake passage member 12F, a main body 16, and an exhaust passage member 18. However, these members may be formed as a single unit. The intake passage member 12F has an inner cylinder portion 85 in its downstream portion. The inner cylinder portion 85 is formed in a cylindrical shape and extends axially inside the housing chamber 40. Although not particularly limited, the outer diameter of the inner cylinder portion 85 may be smaller than the outer diameter of the other parts of the intake passage member 12F. In another example, the intake passage member 12F, including the inner cylinder portion 85, may be formed to have a constant outer diameter.

[0055] The downstream portion and inner cylinder portion 85 of the intake air passage member 12F are housed in the housing chamber 40 of the main body portion 16. A compressed air passage 36 is formed between the intake air passage member 12F and the inner cylinder portion 85 and the inner surface 40a of the housing chamber 40. A circular ring-shaped first passage block 84 is arranged in the compressed air passage 36. Such a first passage block 84 is another example of the configuration of the flow guide member 74.

[0056] As shown in Figure 15A, the first flow channel block 84 is formed in a cylindrical shape. The first flow channel block 84 is positioned to fill the gap between the inner surface 40a of the housing chamber 40 and the outer surface 85a of the inner cylinder portion 85. The first flow channel block 84 has an upstream end face 86, a downstream end face 88, an outer surface 90, a central through hole 92, and a plurality of helical holes 94.

[0057] The upstream end face 86 is located on the upstream side of the first flow channel block 84, and the downstream end face 88 is located on the downstream side of the first flow channel block 84. The position of the downstream end face 88 coincides with the position of the downstream end of the inner cylinder portion 85. However, the position of the downstream end face 88 does not need to coincide with the position of the downstream end of the inner cylinder portion 85, and the inner cylinder portion 85 may protrude downstream beyond the downstream end face 88. The upstream end face 86 and the downstream end face 88 are formed, for example, by planes perpendicular to the central axis C.

[0058] The outer circumferential surface 90 is in surface contact with the inner surface 40a of the containment chamber 40. The outer circumferential surface 90 and the inner surface 40a may be in airtight contact. The central through-hole 92 is located in the center of the first flow path block 84 and penetrates the first flow path block 84 in the axial direction. The inner cylinder portion 85 is inserted into the central through-hole 92. The central through-hole 92 is in surface contact with the inner cylinder portion 85. The central through-hole 92 and the inner cylinder portion 85 may be in airtight contact.

[0059] The spiral holes 94 are located on the outer periphery of the central through hole 92 and are provided in multiple locations at circumferential intervals so as to surround the central through hole 92. In the illustrated example, three spiral holes 94 are formed, but the number of spiral holes 94 may be two or four or more. The spiral holes 94 extend so as to form a spiral around the central axis C, with their third centerline D (see Figure 15B).

[0060] As shown in Figure 15B, each helical hole 94 has an upstream opening 94a located on the upstream side and a downstream opening 94b located on the downstream side. The inner diameter of the downstream opening 94b is larger than the inner diameter of the upstream opening 94a. The inner diameter of the helical hole 94 gradually increases from the upstream opening 94a to the downstream opening 94b. A helical groove 94d is formed on the inner circumferential surface 94c that forms the helical hole 94. The helical groove 94d is formed in a spiral shape with respect to the third center line D of the helical hole 94, and imparts a helical flow to the compressed air passing through the helical hole 94. The first flow channel block 84 as described above is manufactured, for example, by a three-dimensional molding device or the like.

[0061] As shown in Figure 15A, in this embodiment of the negative pressure generating device 10F, the compressed air passage 36 is blocked by the first passage block 84. Therefore, most of the compressed air is injected through the spiral hole 94 towards the exhaust passage 52.

[0062] The compressed air ejected from the spiral hole 94 creates a tornado-like flow downstream of the intake passage member 12F due to its spiral motion. This tornado-like flow of compressed air has strong directionality, and its flow direction is less likely to be disturbed. Therefore, the compressed air can efficiently direct the air flowing in from the intake passage 20 to the downstream side. Consequently, the negative pressure generator 10F of this embodiment can further improve the efficiency of compressed air utilization.

[0063] (Eighth Embodiment) As shown in Figures 16 to 18, the negative pressure generating device 10G of this embodiment includes a second flow path block 96, which is another example of the configuration of the flow guide member 74. In the configuration of the negative pressure generating device 10G, components that are the same as the corresponding components of the negative pressure generating device 10 described with reference to Figures 1A and 1B are denoted by the same reference numerals and their detailed description is omitted.

[0064] As shown in Figure 16, the negative pressure generating device 10G comprises an intake passage member 12F, a main body 16, and an exhaust passage member 18. In the illustrated example, the intake passage member 12F, the main body 16, and the exhaust passage member 18 are integrally connected and formed. However, these members may be configured as separate parts. In this embodiment, the intake passage member 12F does not protrude into the housing chamber 40 of the main body 16. Inside the intake passage member 12F, a first intake passage 20a is formed, extending along the central axis C.

[0065] In this embodiment, a second flow path block 96 is arranged in the housing chamber 40 of the main body 16. The second flow path block 96 includes a second intake flow path 20b that penetrates along the central axis C. The second intake flow path 20b communicates with the first intake flow path 20a inside the intake flow path member 12F. The intake flow path 20 in this embodiment is composed of the first intake flow path 20a and the second intake flow path 20b.

[0066] The second flow path block 96 includes an upstream wall 98, an intermediate section 100, and a downstream wall 102. The upstream wall 98 and the downstream wall 102 are formed in a disc shape having a larger outer diameter than the intermediate section 100 and are connected to each other via the intermediate section 100. The upstream wall 98 is positioned upstream of the supply flow path 14a of the supply port 14 and abuts against the upstream end of the containment chamber 40. The upstream wall 98 has a packing 104 on its outer circumference, which seals the upstream side of the compressed air flow path 36. The intermediate section 100 is formed in a cylindrical shape and extends downstream from the upstream wall 98. The outer diameter of the intermediate section 100 is smaller than the inner diameter of the containment chamber 40. The compressed air flow path 36 is formed between the outer surface 100a of the intermediate section 100 and the inner surface 40a of the containment chamber 40. The supply flow path 14a opens to the outside of the intermediate section 100.

[0067] The downstream wall 102 is located downstream of the supply passage 14a. The outer circumference of the downstream wall 102 abuts against the inner surface 40a of the containment chamber 40. The downstream wall 102 has a packing 106 on its outer circumference, and seals the downstream side of the compressed air passage 36 through the packing 106.

[0068] The second flow path block 96 includes a central through-hole 108 extending along the central axis C and an inclined hole 110 penetrating the downstream wall 102. The central through-hole 108 extends along the central axis C and penetrates the upstream wall 98, the intermediate section 100, and the downstream wall 102 in the axial direction. The central through-hole 108 forms the second intake flow path 20b.

[0069] The inclined holes 110 are located outside the central through-hole 108. In the illustrated example, three inclined holes 110 are arranged at an angle of 120° in the circumferential direction. However, the number of inclined holes 110 is not limited to three. The inner diameter of the inclined holes 110 is smaller than that of the central through-hole 108. The inclined holes 110 have an upstream opening 110a that opens to the upstream end 102a of the downstream wall 102, and a downstream opening 110b that opens to the downstream end 102b of the downstream wall 102. The inclined holes 110 extend linearly from the upstream opening 110a to the downstream opening 110b.

[0070] As shown in Figure 17A, when viewing the downstream wall 102 from the downstream side in the axial direction, the circumferential position of the downstream opening 110b is shifted by θ2° in a predetermined direction from the circumferential position of the upstream opening 110a. Therefore, the inclined hole 110 is inclined in the circumferential direction. Such an inclined hole 110 can generate a spiral flow of compressed air.

[0071] As shown in Figure 17B, the radial position of the downstream opening 110b is located closer to the central axis C than the radial position of the upstream opening 110a. Therefore, the inclined hole 110 is inclined so that the downstream side approaches the central axis C. Such an inclined hole 110 can inject spiral compressed air so that it converges near the central axis C.

[0072] The negative pressure generator 10G of this embodiment is driven by compressed air supplied through the supply passage 14a. The compressed air introduced into the compressed air passage 36 is injected downstream through the inclined holes 110 in the downstream wall 102. The inclined holes 110 guide the flow of compressed air in a spiral shape around the central axis C, depending on their inclination direction. The inclined holes 110 also inject the spiral compressed air so that it converges near the central axis C. As a result, the kinetic energy of the spiral compressed air directed downstream is efficiently transferred to the air that has passed through the intake passage 20. In this way, the negative pressure generator 10G of this embodiment can further increase the efficiency of compressed air utilization.

[0073] (Ninth Embodiment) As shown in Figure 19, the negative pressure generator 10H of this embodiment has a third flow path block 84H attached to the compressed air flow path 36. In the configuration of the negative pressure generator 10H, components that are the same as those in the corresponding configuration of the negative pressure generator 10F described with reference to Figures 15A and 15B are denoted by the same reference numerals and their detailed description is omitted.

[0074] The negative pressure generator 10H of this embodiment has basically the same configuration as the negative pressure generator 10F. However, the negative pressure generator 10H is configured by replacing the first flow path block 84 of the negative pressure generator 10F with a third flow path block 84H.

[0075] The third flow channel block 84H is yet another configuration example of the flow guide member 74. The third flow channel block 84H has a plurality of inclined holes 112 around the central through hole 92.

[0076] The inclined holes 112 are located on the outer periphery of the central through-hole 92 and are provided in multiple locations spaced apart in the circumferential direction, surrounding the central through-hole 92. In the illustrated example, three inclined holes 112 are formed, but the number of inclined holes 112 may be two or four or more. The inner diameter of the inclined holes 112 is smaller than the inner diameter of the central through-hole 92. The centerline of the inclined holes 112 extends in a straight line. The circumferential position of the upstream opening 112a of the inclined hole 112 is shifted in a predetermined direction in the circumferential direction relative to the circumferential position of the downstream opening 112b. Also, the radial position of the downstream opening 112b of the inclined hole 112 is closer to the central axis C than the radial position of the upstream opening 112a. In this way, the inclined holes 112 are inclined with respect to the central axis C. Such inclined holes 112 inject spiral compressed air centered on the central axis C, converging it in the vicinity of the central axis C.

[0077] Furthermore, in this embodiment, the inclined hole 112 has a smaller inner diameter at the downstream opening 112b than at the upstream opening 112a. The inclined hole 112 is formed in a tapered shape, with the inner diameter gradually decreasing from the upstream opening 112a to the downstream opening 112b. Such an inclined hole 112 can increase the flow velocity of compressed air injected from the inclined hole 112 by restricting the compressed air.

[0078] The compressed air ejected from the inclined hole 112 creates a tornado-like flow downstream of the intake passage member 12F through a helical motion. This tornado-like flow of compressed air has strong directionality, and its flow direction is less likely to be disturbed. Therefore, the compressed air can efficiently direct the air flowing in from the intake passage 20 to the downstream side. Consequently, the negative pressure generator 10G of this embodiment can further increase the efficiency of compressed air utilization.

[0079] (Tenth Embodiment) As shown in Figure 20, the negative pressure generating device 10I of this embodiment has a porous block 114 formed of a porous material in the compressed air passage 36. In the configuration of the negative pressure generating device 10I, components that are the same as the corresponding components of the negative pressure generating device 10 described with reference to Figures 1A and 1B are denoted by the same reference numerals and their detailed description is omitted.

[0080] The porous block 114 is positioned to seal the compressed air passage 36 formed between the nozzle 34 and the containment chamber 40. The porous block 114 is positioned near the outlet 36a. The porous block 114 is formed in a cylindrical shape that surrounds the nozzle 34. The downstream end 114a of the porous block 114 is positioned at the same axial position as the downstream end 12c of the nozzle 34 (intake passage member 12).

[0081] The porous block 114 is composed of a porous body having numerous open pores that allow compressed air to flow from upstream to downstream. Such a porous body can be formed by sintering powdered metal, ceramics, or resin. The porous block 114 is not limited to a single layer of porous body, but may be composed of multiple porous bodies stacked on top of each other. Furthermore, the porous block 114 is not limited to a porous body, but may be replaced by a pseudo-porous structure formed by stacking multiple meshes (wire mesh) of a certain pitch in the thickness direction. In addition, the porous block 114 may be a structure composed of stacked metal plates with perforations formed on them. Furthermore, the porous block 114 may be composed of a large number of spheres filled inside a cage-like container of a predetermined shape.

[0082] The negative pressure generator 10I of this embodiment can improve the efficiency of compressed air utilization by rectifying the flow of compressed air supplied from the supply channel 14a as it passes through the porous block 114, thereby equalizing the flow of compressed air. Furthermore, the porous block 114 removes foreign matter contained in the compressed air and exerts a cooling effect as the compressed air expands, contributing to the stabilization of the factory environment. In addition, the porous block 114 reduces noise generated by compressed air, maintaining a favorable working environment in the factory.

[0083] (Eleventh Embodiment) As shown in Figure 21, the negative pressure generating device 10J of this embodiment injects compressed air through a porous block 116 formed of a porous material. In the configuration of the negative pressure generating device 10J, components that are the same as those in the corresponding components of the negative pressure generating device 10I described with reference to Figure 20 are denoted by the same reference numerals and their detailed description is omitted.

[0084] As shown in Figure 21, the porous block 116 is positioned to fill the compressed air passage 36 formed in the gap between the containment chamber 40 and the intake passage member 12. The porous block 116 is formed by sintering a large number of particles, and open pores communicating with each other are formed between the particles. Therefore, compressed air can flow through the porous block 116 from the upstream side to the downstream side through the open pores. The diameter of the particles constituting the porous block 116 (particle diameter) gradually increases from the upstream side to the downstream side. The pore diameter of the open pores formed between the particles also gradually increases from the upstream side to the downstream side. Such a porous block 116 is manufactured by joining and integrating sintered blocks with different particle diameters.

[0085] Other configurations of the porous block 116, which are not limited to this example, are listed below. The porous block 116 may be constructed, for example, by stacking multiple metal meshes with different pitches. Alternatively, the porous block 116 may be formed by stacking multiple punching plates with different pore diameters. Furthermore, the porous block 116 may be constructed by stacking multiple spheres of different diameters in the axial direction inside a cage-like container of a predetermined shape.

[0086] The negative pressure generator 10J described above injects compressed air through the porous block 116. Furthermore, because the porous block 116 exhibits a cooling effect during the expansion of compressed air, the negative pressure generator 10J can improve the efficiency of compressed air utilization by cooling the compressed air even when high-temperature compressed air is supplied. This suppresses turbulence in the compressed air flow and energy loss due to the rise in temperature of the compressed air. In addition, the porous block 116, whose pore size increases from upstream to downstream, improves the flow velocity of the injected compressed air. Furthermore, since the porous block 116 can adsorb foreign matter contained in the compressed air, it is suitable for use in clean environments.

[0087] With regard to the above embodiments, the following additional information is disclosed.

[0088] (Note 1) The negative pressure generating device (10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10I, 10J) of the present disclosure comprises an intake passage (20) extending along a central axis (C), a compressed air passage (36) encircling the intake passage in an annular manner, an exhaust passage (52) connected downstream of the intake passage and the compressed air passage, and a supply passage (14a) supplying compressed air to the compressed air passage, wherein the supply passage is connected to the compressed air passage in a direction such that the extension of the first center line (B) of the supply passage does not intersect with the central axis.

[0089] According to the above configuration, the compressed air flowing in from the supply channel flows spirally along the compressed air channel, thereby suppressing turbulence in the compressed air flow. As a result, the negative pressure generator can reduce the energy loss of compressed air and improve the efficiency of compressed air utilization.

[0090] (Note 2) In the negative pressure generating device described in Note 1, the tangent at a predetermined point on the annular second center line (E) of the compressed air passage in a cross section perpendicular to the central axis may be parallel to the first center line of the supply passage. With this configuration, the compressed air flows in in the tangential direction of the compressed air passage, so that flow turbulence is suppressed and the compressed air can flow smoothly in a spiral manner through the compressed air passage.

[0091] (Note 3) In the negative pressure generating device described in Note 1 or 2, the supply passages may be provided in multiple locations spaced apart in the circumferential direction of the compressed air passage. This configuration suppresses energy loss of the compressed air.

[0092] (Note 4) A negative pressure generating device according to any one of Notes 1 to 3, wherein the supply passage is inclined with respect to a cross section perpendicular to the central axis, and the downstream end of the supply passage is located in a direction closer to the exhaust passage than the upstream end of the supply passage. With this configuration, since the supply passage predirects the injection direction of the compressed air toward the downstream, turbulence in the flow of compressed air is suppressed, and the negative pressure generating device can deliver compressed air more smoothly.

[0093] (Note 5) A negative pressure generating device according to any one of Notes 1 to 4, wherein the supply passage may have a tapered section (70) formed at the connection point with the compressed air passage, the inner diameter of which gradually widens toward the compressed air passage. This negative pressure generating device suppresses turbulence in the flow of compressed air at the connection point between the supply passage and the compressed air passage, thereby suppressing energy loss of the compressed air.

[0094] (Note 6) A negative pressure generating device described in any one of Notes 1 to 5 may be provided in the compressed air passage with a flow guide member (74) that guides the flow of compressed air in a spiral shape around the central axis. This negative pressure generating device can increase the efficiency of compressed air utilization by generating a spiral airflow directed downstream.

[0095] (Note 7) In the negative pressure generating device described in Note 6, the flow guide member may have spiral irregularities (76) formed on the wall surface forming the compressed air passage and extending spirally around the central axis. This negative pressure generating device can generate a spiral flow of compressed air in the compressed air passage with a simple configuration.

[0096] (Note 8) In the negative pressure generating device described in Note 6, the flow guide member may be a flow path block (84, 84H, 96) arranged in the compressed air flow path and having a plurality of through holes formed therein for guiding the compressed air. This negative pressure generating device can generate a spiral flow of compressed air through the through holes.

[0097] (Note 9) In the negative pressure generating device described in Note 8, the through hole may be a spiral hole (94) extending spirally around the central axis. This negative pressure generating device can generate a spiral flow of compressed air through the spiral hole.

[0098] (Note 10) In the negative pressure generating device described in Note 9, the inner diameter of the helical hole may gradually increase from the upstream opening (94a) to the downstream opening (94b). This negative pressure generating device can efficiently convert the pressure of compressed air into kinetic energy.

[0099] (Note 11) In the negative pressure generating device described in Note 9 or 10, the flow path block may have a helical groove (94d) formed on the inner circumferential surface (94c) that forms the helical hole, which is spirally formed with respect to the third center line (D) of the helical hole. This negative pressure generating device can direct the flow of compressed air more strongly in the direction of the helical hole by the helical groove, and can more efficiently transfer the kinetic energy of the compressed air to the air that has passed through the intake flow path.

[0100] (Note 12) The negative pressure generating device described in Note 8 may be an inclined hole (110, 112) such that the circumferential position of the upstream opening (110a, 112a) with respect to the central axis is different from the circumferential position of the downstream opening (110b, 112b) with respect to the central axis. This negative pressure generating device can generate a spiral flow of compressed air with a linearly extending inclined hole that is easy to manufacture.

[0101] (Note 13) The negative pressure generating device described in Note 12, wherein the inclined hole may be further inclined in a direction such that the downstream opening is closer to the central axis than the upstream opening. This negative pressure generating device can generate a spiral flow of compressed air that converges near the central axis, thereby increasing the efficiency of compressed air utilization.

[0102] (Note 14) In the negative pressure generating device described in Note 13, the inclined hole may have an inner diameter that gradually decreases from the upstream opening to the downstream opening. This negative pressure generating device can strengthen the helical flow of compressed air that converges near the central axis.

[0103] (Note 15) A negative pressure generating device described in any one of Notes 1 to 5 may be provided with porous blocks (114, 116) arranged in the compressed air passage and having open holes through which the compressed air passes. This negative pressure generating device can improve the efficiency of compressed air utilization by regulating the flow of compressed air with the porous blocks. In addition, the negative pressure generating device can remove foreign matter from the compressed air, exert a cooling effect to lower the temperature of the compressed air, and suppress the noise of the compressed air.

[0104] (Note 16) In the negative pressure generating device described in Note 15, the pore diameter of the open holes in the porous block may gradually increase from upstream to downstream. This negative pressure generating device can smoothly expand the compressed air by increasing the pore diameter of the open holes along the direction of movement of the compressed air, thereby increasing the efficiency of compressed air utilization. Furthermore, the porous block contributes to stabilizing the environment inside the factory by exhibiting cooling, foreign matter removal, and noise reduction effects.

[0105] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above.

[0106] 10, 10A-10J... Negative pressure generator 14a... Supply channel 20... Intake channel 36... Compressed air channel 52... Exhaust channel 70... Tapered section 74... Flow guide member 94... Helical hole 110, 112... Inclined holes 114, 116... Porous block

Claims

1. A negative pressure generating device (10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10I, 10J) comprising: an intake passage (20) extending along a central axis (C); a compressed air passage (36) surrounding the intake passage in an annular shape; an exhaust passage (52) connected downstream of the intake passage and the compressed air passage; and a supply passage (14a) supplying compressed air to the compressed air passage, wherein the supply passage is connected to the compressed air passage in a direction such that the extension of the first center line (B) of the supply passage does not intersect with the central axis.

2. A negative pressure generating device according to claim 1, wherein, in a cross section perpendicular to the central axis, the tangent at a predetermined location on the annular second centerline of the compressed air passage is parallel to the first centerline of the supply passage.

3. A negative pressure generating device according to claim 2, wherein the supply passages are provided in a plurality at intervals in the circumferential direction of the compressed air passage.

4. A negative pressure generating device according to claim 1, wherein the supply channel is inclined with respect to a cross section perpendicular to the central axis, and the downstream end of the supply channel is located in a direction closer to the exhaust channel than the upstream end of the supply channel.

5. A negative pressure generating device according to claim 1, wherein the supply channel has a tapered portion (70) formed at the connection point with the compressed air channel, the inner diameter of which gradually widens toward the compressed air channel.

6. A negative pressure generating device according to any one of claims 1 to 5, wherein the compressed air passage is provided with a flow guide member (74) that guides the flow of the compressed air in a spiral shape with respect to the central axis.

7. A negative pressure generating device according to claim 6, wherein the flow guide member is formed on the wall surface forming the compressed air passage and has spiral irregularities (76) extending spirally around the central axis.

8. A negative pressure generating device according to claim 6, wherein the flow guide member is a flow path block (84, 84H, 96) arranged in the compressed air flow path and having a plurality of through holes formed therein for guiding the compressed air.

9. A negative pressure generating device according to claim 8, wherein the through hole is a spiral hole (94) extending spirally around the central axis.

10. A negative pressure generating device according to claim 9, wherein the spiral hole has an inner diameter that gradually expands from the upstream opening (94a) to the downstream opening (94b).

11. A negative pressure generating device according to claim 9, wherein the flow path block has a helical groove (94d) formed on the inner circumferential surface (94c) that forms the helical hole, such that it spirals in a helical manner with respect to the third center line (D) of the helical hole.

12. A negative pressure generating device according to claim 8, wherein the through holes are inclined holes (110, 112) that are inclined such that the circumferential position of the upstream openings (110a, 112a) with respect to the central axis is different from the circumferential position of the downstream openings (110b, 112b) with respect to the central axis.

13. A negative pressure generating device according to claim 12, wherein the inclined hole is further inclined such that the downstream opening approaches the central axis more closely than the upstream opening.

14. A negative pressure generating device according to claim 13, wherein the inclined hole has an inner diameter that gradually decreases from the upstream opening toward the downstream opening.

15. A negative pressure generating device according to any one of claims 1 to 5, comprising porous blocks (114, 116) arranged in the compressed air passage and having open holes through which the compressed air passes.

16. A negative pressure generating device according to claim 15, wherein the porous block has a pore diameter that gradually increases from upstream to downstream.

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