Negative-pressure-generating device

Abstract

A negative-pressure-generating device (10) comprises: an air intake flow passage (54); a compressed air flow passage (50) surrounding the periphery of the air intake flow passage (54); an exhaust flow passage (56) provided downstream of the air intake flow passage (54) and the compressed air flow passage (50); and a supply flow passage (24a) for supplying compressed air to the compressed air flow passage (50). The compressed air flow passage (50) is provided with a flow guide member (58) that guides the flow of compressed air in a spiral shape centered on a central axis (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 Application Laid-Open No. 2018-511733 shows an example of a negative pressure generating device. The negative pressure generating device injects compressed air from a gap between an intake passage member that sucks in air and an exhaust passage member that exhausts air toward the exhaust passage member. When the injected compressed air flows toward the exhaust passage member, it draws the air in the intake passage member toward the exhaust passage member, thereby generating negative pressure in the intake passage member. Also, from the exhaust passage member, air having a flow rate larger than the supply amount of the compressed air is exhausted.

[0003] In the negative pressure generating device, the compressed air supplied from the intake passage member has its pressure (compression energy) converted into flow velocity (kinetic energy) in the process of flowing from the supply passage to the exhaust passage. However, if turbulence occurs in the flow of the compressed air flowing from the supply passage to the exhaust passage, energy loss occurs. As a result, a decrease in the exhaust flow rate with respect to the supply amount of the compressed air and suppression of the generated negative pressure 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-described problems.

[0005] A first 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 compressed air passage is provided with a flow guiding member that guides the flow of the compressed air in a spiral shape centered on the central axis, and is a negative pressure generating device.

[0006] A second aspect of the present disclosure is a negative pressure generating device comprising: an intake passage extending along a central axis; a compressed air passage encircling the intake passage in an annular manner; an exhaust passage connected downstream of the intake passage and the compressed air passage; a supply passage for supplying compressed air to the compressed air passage; and a porous block disposed in the compressed air passage and having open holes for allowing the compressed air to pass through.

[0007] According to this disclosure, a negative pressure generating device with excellent compressed air utilization efficiency is provided.

[0008] Figure 1 is an explanatory diagram showing application examples of the negative pressure generating device according to the first to tenth embodiments. Figure 2 is a longitudinal cross-sectional view of the negative pressure generating device according to the first embodiment. Figure 3A is a plan view of the first flow path block of Figure 2 viewed from the downstream side in the axial direction, and Figure 3B is a cross-sectional view along the line IIIB-IIIB in Figure 3A. Figure 4 is a perspective view of the first flow path block of Figure 2. Figure 5 is an explanatory diagram showing the tornado-shaped jet generated inside the negative pressure generating device by the first flow path block of Figure 2. Figure 6A is a plan view of the flow path block according to a comparative example viewed from the axial direction, and Figure 6B is an explanatory diagram showing the jet inside the negative pressure generating device according to a comparative example. Figure 7A is a cross-sectional view showing the arrangement of the supply ports of the negative pressure generating device according to the second embodiment, and Figure 7B is a cross-sectional view showing the arrangement of the supply ports of the negative pressure generating device according to the third embodiment. Figure 8 is a longitudinal cross-sectional view of the negative pressure generating device according to the fourth embodiment. Figure 9 is a longitudinal cross-sectional view of the negative pressure generating device according to the fifth embodiment. Figure 10A is a cross-sectional view of a negative pressure generating device according to the sixth embodiment, and Figure 10B is a perspective view of the nozzle in Figure 10A. Figure 11A is a schematic explanatory diagram of a negative pressure generating device according to the seventh embodiment, and Figure 11B is an explanatory diagram of the spiral hole in Figure 11A. Figure 12 is a schematic explanatory diagram of a negative pressure generating device according to the eighth embodiment. Figure 13 is a cross-sectional view of a negative pressure generating device according to the ninth embodiment. Figure 14 is a cross-sectional view of a negative pressure generating device according to the tenth embodiment.

[0009] In the following embodiments, examples of negative pressure generators 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, and 10I are provided, which generate negative pressure and airflow in a predetermined direction by supplying compressed air. These negative pressure generators 10, 10A to 10I are connected, for example, between the suction tank 13 and the silencer 14 of a dust collector 12, as shown in Figure 1. Compressed air is supplied to the negative pressure generators 10, 10A to 10I from a compressed air supply source 16, such as a factory's compressed air line, and the negative pressure generators 10, 10A to 10I exhaust the suction tank 13. The negative pressure generators 10, 10A to 10I are also connected only to the compressed air supply source 16 and used as blowers to blow away dust, water droplets, etc., adhering to the surface of a workpiece by utilizing the discharged airflow.

[0010] In this specification, the negative pressure generating devices 10, 10A to 10I 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 generating devices 10, 10A to 10I draw in air, and downstream is the direction in which the negative pressure generating devices 10, 10A to 10I 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.

[0011] (First Embodiment) As shown in Figure 2, the negative pressure generating device 10 according to the first embodiment includes an intake passage member 18, a main body 20, an exhaust passage member 22, and a supply port 24. The intake passage member 18, the main body 20, and the exhaust passage member 22 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.

[0012] The intake passage member 18 is located on the upstream side of the negative pressure generating device 10. In one example, the intake passage member 18 is integrally connected to the main body 20. The downstream end of the intake passage member 18 is connected to the stepped portion 28 of the main body 20. The intake passage member 18 has a first intake passage 26 formed therein to draw air into the negative pressure generating device 10. The first intake passage 26 extends axially and penetrates the interior of the intake passage member 18 in the axial direction. The first intake passage 26 communicates with the second intake passage 44, which will be described later.

[0013] The main body 20 is located near the axial center of the negative pressure generating device 10 and connects the intake passage member 18 and the exhaust passage member 22. The main body 20 has a larger outer diameter than the intake passage member 18 and is connected to the intake passage member 18 via a stepped portion 28. The main body 20 has a cylindrical body portion 30 and a reduced diameter portion 32 formed downstream of the body portion 30.

[0014] The body portion 30 extends downstream from the stepped portion 28. The body portion 30 extends in a cylindrical shape while maintaining a constant inner diameter in the axial direction. The reduced diameter portion 32 extends downstream from the downstream end of the body portion 30. The reduced diameter portion 32 narrows in a conical shape towards the downstream side. The downstream end of the reduced diameter portion 32 is formed to have the same outer diameter as the exhaust flow path member 22 and is connected to the exhaust flow path member 22. Inside the main body portion 20, a housing chamber 34 is formed, surrounded by the stepped portion 28, the body portion 30, and the reduced diameter portion 32. The first flow path block 36 is housed in the housing chamber 34.

[0015] As shown in Figures 2 to 4, the first flow path block 36 has an upstream wall 38, an intermediate section 40, a downstream wall 42, a second intake flow path 44, and an inclined hole 46. The upstream wall 38 is a disc-shaped member located on the upstream side and is positioned in contact with the stepped section 28. The outer circumference of the upstream wall 38 is in contact with the inner circumferential surface 30a of the body section 30. A packing 48 is attached to the outer circumference of the upstream wall 38. The packing 48 airtightly seals the gap between the inner circumferential surface 30a and the upstream wall 38, preventing compressed air from leaking upstream.

[0016] The intermediate section 40 is a cylindrical portion extending axially, and extends downstream from the downstream end of the upstream wall 38. The downstream end of the intermediate section 40 is connected to the downstream wall 42. The outer diameter of the intermediate section 40 is smaller than the outer diameter of the upstream wall 38 and the outer diameter of the downstream wall 42, and is spaced inward from the inner circumferential surface 30a of the body section 30. A compressed air passage 50 is formed between the outer circumferential surface 40a of the intermediate section 40 and the inner circumferential surface 30a of the body section 30. The compressed air passage 50 surrounds the intake passage 54, which will be described later, in an annular manner.

[0017] The downstream wall 42 is formed in a disc shape, and its outer circumference abuts against the inner circumferential surface 30a of the body 30. A packing 52 is attached to the outer circumference of the downstream wall 42. The packing 52 airtightly seals the gap between the inner circumferential surface 30a and the downstream wall 42.

[0018] The second intake passage 44 is formed in the center of the first passage block 36 and penetrates the upstream wall 38, the intermediate section 40, and the downstream wall 42 in the axial direction. The second intake passage 44 communicates with the first intake passage 26. The first intake passage 26 and the second intake passage 44 constitute the intake passage 54 of this embodiment.

[0019] Multiple inclined holes 46 are formed in the downstream wall 42. In the illustrated example, three inclined holes 46 are arranged around the intake passage 54 at equal intervals in the circumferential direction (for example, at an angle of 120°).

[0020] The inclined hole 46 has an upstream opening 46a that opens to the upstream side and a downstream opening 46b that opens to the downstream side. The inclined hole 46 extends linearly between the upstream opening 46a and the downstream opening 46b while maintaining a constant inner diameter. The upstream opening 46a communicates with the compressed air passage 50. The downstream opening 46b communicates with the downstream portion of the containment chamber 34. The downstream opening 46b communicates with the exhaust passage 56, which will be described later, via the downstream portion of the containment chamber 34. Such an inclined hole 46 can be easily formed by drilling the downstream wall 42.

[0021] As shown in Figure 3A, the circumferential position of the downstream opening 46b is shifted by an angle θ2 in a predetermined direction relative to the circumferential position of the upstream opening 46a. Therefore, the inclined hole 46 is inclined to rotate diagonally around the central axis C as it moves downstream.

[0022] Furthermore, as shown in Figures 3B and 4, the radial position of the downstream opening 46b is offset from the radial position of the upstream opening 46a, and is positioned closer to the central axis C. Therefore, the inclined hole 46 is inclined by a predetermined angle θ1 so as it moves downstream, it approaches the central axis C.

[0023] The downstream wall 42 having the inclined hole 46 described above constitutes the flow guide member 58 of this embodiment, and guides the compressed air to generate a spiral flow around the central axis C.

[0024] As shown in Figure 2, the exhaust passage member 22 is connected to the downstream end of the main body 20. The exhaust passage member 22 may be configured to be integrally connected with the main body 20, as shown in the figure. However, the exhaust passage member 22 may be configured separately from the main body 20. The exhaust passage member 22 has an exhaust passage 56 extending axially in its center. The exhaust passage 56 extends coaxially with the central axis C and penetrates the exhaust passage member 22 in the axial direction.

[0025] The supply port 24 is a portion to which piping (not shown) is connected and to which compressed air is supplied through the piping. The supply port 24 is provided on the outer circumference of the main body 20. The supply port 24 is formed integrally with the main body 20 on the outer circumference of the body 30. Inside the supply port 24, there is a supply passage 24a that guides compressed air to the compressed air passage 50. The supply passage 24a is located outside the intermediate portion 40 of the first passage block 36 and communicates with the compressed air passage 50. In this embodiment, the first center line B of the supply passage 24a is oriented radially with respect to the central axis C.

[0026] The negative pressure generating device 10 of this embodiment is configured as described above. The operation of the negative pressure generating device 10 will be described below.

[0027] As shown in Figure 5, the negative pressure generator 10 operates by supplying compressed air to the supply port 24. The compressed air supplied to the supply port 24 flows into the compressed air passage 50 through the supply passage 24a. The compressed air that flows into the compressed air passage 50 is injected into the downstream portion of the housing chamber 34 through the inclined hole 46 in the downstream wall 42.

[0028] Due to the inclination of the inclined holes 46, the compressed air is injected in a spiral manner around the central axis C and converges towards the center of the central axis C. The compression energy of the compressed air is converted into velocity, and depending on the compression ratio, an airflow that reaches the speed of sound is generated. In this embodiment, the inclined holes 46 generate an airflow that converges in a tornado shape near the central axis C, as shown in the figure. This creates a negative pressure in the downstream part of the containment chamber 34, drawing air in from the intake passage 54. Furthermore, due to the viscosity of the air, air flows into the exhaust passage 56, and the air drawn in from the intake passage 54 and the air injected from the inclined holes 46 are discharged from the exhaust passage 56. In this embodiment, the negative pressure generator 10 can efficiently utilize compressed air to generate negative pressure by using a high-speed airflow that converges in a tornado shape near the central axis C.

[0029] In the comparative example negative pressure generator 100 shown in Figure 6A, the through-holes 104 of the flow path block 102 are not formed with a slope that creates a flow that swirls with respect to the central axis C. As shown in Figure 6B, the air injected from such through-holes 104 converges near the central axis C and then generates turbulence. As a result, kinetic energy is easily lost from the airflow generated from the compressed air, and the utilization efficiency of the compressed air decreases.

[0030] In contrast, as shown in Figure 5, the negative pressure generator 10 of this embodiment can prevent the generation of turbulence by using a tornado-shaped airflow that converges near the central axis C, thereby increasing the efficiency of compressed air utilization compared to the negative pressure generator 100 of the comparative example.

[0031] (Second Embodiment) As shown in Figure 7A, the negative pressure generating device 10A of this embodiment differs from the negative pressure generating device 10 of the first embodiment in that it has three supply ports 24 for supplying compressed air. Figure 7A shows a cross-section perpendicular to the axial direction. In this embodiment, only the structure near the supply ports 24 is shown, and the explanation of other components is omitted.

[0032] As shown in the figure, the three supply ports 24 are arranged at equal intervals around the main body 20 at an angle of 120°. The supply flow path 24a of each supply port 24 has its first centerline B oriented radially with respect to the central axis C.

[0033] According to the negative pressure generating device 10A of this embodiment, a large flow rate of compressed air can be supplied by providing multiple supply ports 24.

[0034] (Third Embodiment) As shown in Figure 7B, the negative pressure generating device 10B of this embodiment differs from the negative pressure generating device 10 of the first embodiment in that it has four supply ports 24 for supplying compressed air. Figure 7B shows a cross-section perpendicular to the axial direction. In this embodiment, only the structure near the supply ports 24 is shown, and the explanation of other configurations is omitted.

[0035] As shown in the figure, the four supply ports 24 are arranged at equal intervals around the main body 20 at a 90° angle. The supply flow path 24a of each supply port 24 has its first centerline B oriented radially with respect to the central axis C.

[0036] According to the negative pressure generating device 10B of this embodiment, a large flow rate of compressed air can be supplied by providing multiple supply ports 24. The number of supply ports 24 may be four or more.

[0037] (Fourth Embodiment) As shown in Figure 8, the negative pressure generator 10C of this embodiment differs from the supply port 24 of the negative pressure generator 10 described with reference to Figures 1 to 5 in that the outlet of the supply port 24C is inclined toward the downstream side. In the configuration of the negative pressure generator 10C, the same reference numerals are used for components that are the same as those in the negative pressure generator 10 of the first embodiment, and their detailed descriptions are omitted.

[0038] As shown in Figure 8, the negative pressure generator 10C has a supply port 24C. The supply port 24C is mounted such that the first center line B of its supply channel 24a is inclined at a predetermined angle θ with respect to the central axis C. The first center line B of the supply channel 24a is inclined to move downstream as it approaches the central axis C. The supply channel 24a is inclined such that its downstream end is located further downstream in the axial direction than its upstream end.

[0039] In this embodiment, the supply port 24C directs compressed air downstream in the supply channel 24a and injects it into the compressed air channel 50. The compressed air supplied from the supply port 24C is injected downstream through the inclined hole 46 of the first channel block 36. In the negative pressure generator 10C, since the compressed air is supplied downstream at the supply port 24C, the utilization efficiency of the compressed air can be further increased.

[0040] (Fifth Embodiment) As shown in Figure 9, the negative pressure generating device 10D of this embodiment differs from the negative pressure generating device 10 described with reference to Figures 1 to 5 in that a tapered portion 60 is formed at the outlet of the supply port 24D. In the configuration of the negative pressure generating device 10D, the same reference numerals are used for components that are the same as those in the negative pressure generating device 10 of the first embodiment, and their detailed description is omitted.

[0041] The supply port 24D has a tapered section 60 near the downstream end (outlet) of the supply passage 24a. The tapered section 60 is provided at the connection point between the supply port 24D and the compressed air passage 50. The tapered section 60 has an inclined surface 62 in which the inner diameter of the supply passage 24a gradually widens as it moves inward towards the negative pressure generator 10D. The tapered section 60 suppresses turbulence in the flow of compressed air by gradually expanding the compressed air. As a result, the supply port 24D suppresses energy loss of compressed air. Therefore, the negative pressure generator 10D of this embodiment can increase the efficiency of compressed air utilization.

[0042] (Sixth Embodiment) As shown in FIG. 10A, the negative pressure generating device 10E of this embodiment includes an intake passage member 18E, a main body portion 20, and an exhaust passage member 22. In the configuration of the negative pressure generating device 10E, the same reference numerals are given to the configurations common to the negative pressure generating device 10 of the first embodiment, and detailed descriptions thereof are omitted.

[0043] A part of the downstream side of the intake passage member 18E constitutes a nozzle 64, and the nozzle 64 protrudes into the accommodation chamber 34 of the main body portion 20. The nozzle 64 is spaced inward from the inner surface 20a of the main body portion 20 that forms the accommodation chamber 34. A compressed air passage 50 of this embodiment is formed between the outer surface 64a of the nozzle 64 and the inner surface 20a of the main body portion 20. The compressed air passage 50 annularly surrounds the periphery of the nozzle 64 (and the intake passage 54).

[0044] An intake passage 54 is formed inside the intake passage member 18E. The intake passage 54 axially penetrates the center of the intake passage member 18E. The intake passage 54 opens into the accommodation chamber 34 at the downstream end of the nozzle 64. The intake passage 54 communicates with the exhaust passage 56 through the accommodation chamber 34.

[0045] The outer surface 64a of the nozzle 64 is formed in a substantially conical shape such that the outer diameter gradually decreases toward the downstream side. Such an outer surface 64a of the nozzle 64 forms the compressed air passage 50 together with the inner surface 20a of the main body portion 20 that forms the accommodation chamber 34. A spiral step portion 66 (spiral unevenness) that constitutes the flow guiding member 58 of this embodiment is formed on the outer surface 64a of the nozzle 64.

[0046] As shown in FIG. 10B, the spiral step portion 66 is formed by a stepped portion constituted by a surface having an inclination angle different from the inclination angle of the cone of the nozzle 64. The spiral step portion 66 extends to the downstream end of the nozzle 64 while drawing a spiral around the central axis C. In the illustrated example, the inclination angle of the surface forming the spiral step portion 66 is an inclination angle perpendicular or nearly perpendicular to the axial direction. However, the inclination angle of the surface forming the spiral step portion 66 is not limited to this, and a surface having an angle smaller than the inclination angle of the cone of the nozzle 64 with respect to the axial direction may also be used.

[0047] The configurations of the main body portion 20, the exhaust passage member 22, and the supply port 24 are as described while referring to FIGS. 2 to 5.

[0048] As shown in FIG. 10A, in a portion adjacent to the spiral step portion 66, a portion where the cross-section of the compressed air passage 50 is locally large is formed. By the portion where the cross-section of the compressed air passage 50 is locally large extending spirally, the compressed air flowing through the compressed air passage 50 can be guided spirally. Such a spiral flow of the compressed air can suppress the turbulent flow of the compressed air by generating a jet flow converging in a tornado shape at the jet outlet 50a and downstream thereof, and can efficiently transfer the kinetic energy of the compressed air to the air passing through the intake passage 54, thereby increasing the utilization efficiency of the compressed air. As described above, the negative pressure generating device 10E of the present embodiment can suppress the energy loss of the compressed air and increase the utilization efficiency of the compressed air.

[0049] In the present embodiment, the spiral step portion 66 may be provided on the inner surface 20a side of the main body portion 20 forming the housing chamber 34 instead of the outer peripheral portion of the nozzle 64. Further, the spiral step portion 66 may be provided on both the outer surface 64a of the nozzle 64 and the inner surface 20a of the main body portion 20 forming the housing chamber 34.

[0050] Furthermore, the flow guiding member 58 of the present embodiment is not limited to the spiral step portion 66, and may be constituted by a spiral convex portion or a spiral flow guiding plate or the like formed so as to project from either one or both of the outer surface 64a of the nozzle 64 or the inner surface 20a of the main body portion 20 forming the housing chamber 34.

[0051] (Seventh Embodiment) As shown in FIG. 11A, the negative pressure generating device 10F of the present embodiment includes an intake passage member 18F, a main body portion 20, an exhaust passage member 22, a supply port 24, and a second flow path block 68. In the configuration of the negative pressure generating device 10F, regarding the same configurations as those of the negative pressure generating device 10 described while referring to FIGS. 2 to 5 and the negative pressure generating device 10E described while referring to FIGS. 10A and 10B, the same reference numerals are given and the detailed description thereof is omitted.

[0052] The intake passage member 18F has a portion of its downstream side that penetrates the stepped portion 28 of the main body 20 and is inserted into the interior of the housing chamber 34. The intake passage member 18F may be formed integrally with the main body 20. Since the outer diameter of the intake passage member 18F is smaller than the inner diameter of the housing chamber 34, the outer surface 18a of the intake passage member 18F is spaced inward from the inner surface 20a of the main body 20 that forms the housing chamber 34. A compressed air passage 50 is formed between the outer surface 18a and the inner surface 20a.

[0053] An intake passage 54 is formed in the center of the intake passage member 18F. The intake passage 54 penetrates the intake passage member 18F in the axial direction. The downstream end of the intake passage 54 opens to the downstream side of the containment chamber 34.

[0054] A smaller outer diameter inner cylinder portion 70 is formed in the downstream portion of the intake passage member 18F. The outer diameter of the inner cylinder portion 70 is not limited to the illustrated example, and in another example, the intake passage member 18F, including the inner cylinder portion 70, may be formed with a constant outer diameter. A circular ring-shaped second passage block 68 is fitted into the inner cylinder portion 70. Such a second passage block 68 is another example of the configuration of the flow guide member 58.

[0055] As shown in Figure 11A, the second flow channel block 68 is formed in a cylindrical shape. The second flow channel block 68 fills the gap between the inner surface 20a of the main body portion 20 that forms the housing chamber 34 and the outer surface 70a of the inner cylinder portion 70. The second flow channel block 68 has an upstream end face 68a, a downstream end face 68b, an outer peripheral surface 68c, a central through hole 68d, and a plurality of helical holes 72.

[0056] The upstream end face 68a is located on the upstream side of the second flow channel block 68, and the downstream end face 68b is located on the downstream side of the second flow channel block 68. The position of the downstream end face 68b coincides with the position of the downstream end of the inner cylinder portion 70. However, the position of the downstream end face 68b does not need to coincide with the position of the downstream end of the inner cylinder portion 70. The inner cylinder portion 70 may protrude downstream beyond the downstream end face 68b. The upstream end face 68a and the downstream end face 68b are formed, for example, by a plane perpendicular to the central axis C.

[0057] The outer circumferential surface 68c is in surface contact with the inner surface 20a of the main body 20 that forms the containment chamber 34. The outer circumferential surface 68c and the inner surface 20a may be in airtight contact. The central through hole 68d is located in the center of the second flow path block 68 and penetrates the second flow path block 68 in the axial direction. The inner cylinder portion 70 is inserted into the central through hole 68d. The central through hole 68d is in surface contact with the inner cylinder portion 70. The central through hole 68d and the inner cylinder portion 70 may be in airtight contact.

[0058] The spiral holes 72 are located on the outer periphery of the central through hole 68d and are provided in multiple locations at circumferential intervals surrounding the central through hole 68d. In the illustrated example, three spiral holes 72 are arranged at a 120° angle in the circumferential direction. The number of spiral holes 72 may be two or four or more. Each spiral hole 72 extends from the upstream end face 68a to the downstream end face 68b. The spiral hole 72 extends such that its third centerline D (see Figure 11B) traces a spiral around the central axis C.

[0059] As shown in Figure 11B, each helical hole 72 has an upstream opening 72a that opens to the upstream end face 68a and a downstream opening 72b that opens to the downstream end face 68b. The inner diameter of the downstream opening 72b is larger than the inner diameter of the upstream opening 72a. The inner diameter of the helical hole 72 gradually increases from the upstream opening 72a to the downstream opening 72b. A helical groove 72d is formed on the inner circumferential surface 72c that forms the helical hole 72. The helical groove 72d is formed in a spiral shape with respect to the third center line D of the helical hole 72, and imparts a spiral flow to the compressed air passing through the helical hole 72. The second flow channel block 68 as described above is manufactured, for example, by a three-dimensional molding device or the like.

[0060] As shown in Figure 11A, in this embodiment of the negative pressure generator 10F, the compressed air passage 50 is blocked by the second flow path block 68. Therefore, the compressed air supplied from the supply port 24 is injected through the spiral hole 72 towards the exhaust passage 56.

[0061] The compressed air ejected from the spiral hole 72 generates a tornado-like flow downstream of the intake passage member 18F, converging near the central axis C due to its spiral motion. This tornado-like flow has strong directionality, and its flow direction is less likely to be disturbed. As a result, energy loss of the compressed air is suppressed, and the air flowing in from the intake passage 54 can be efficiently directed downstream. Therefore, the negative pressure generator 10F of this embodiment can further improve the efficiency of compressed air utilization.

[0062] (Eighth Embodiment) As shown in Figure 12, the negative pressure generator 10G of this embodiment differs from the negative pressure generator 10F described with reference to Figure 11A in the third flow path block 68G. In the configuration of the negative pressure generator 10G, components that are the same as those in the corresponding components of the negative pressure generator 10F described with reference to Figure 11A are denoted by the same reference numerals and their detailed description is omitted.

[0063] The third flow path block 68G of the negative pressure generating device 10G is yet another configuration example of the flow guide member 58. The third flow path block 68G is formed in a cylindrical shape and is mounted on the inner cylinder portion 70 of the intake air flow path member 18F. The third flow path block 68G closes the downstream side of the compressed air flow path 50. The third flow path block 68G has a plurality of inclined holes 74 around a central through hole 68d.

[0064] The inclined holes 74 are located on the outer periphery of the central through-hole 68d and are provided in multiple locations spaced apart in the circumferential direction, surrounding the central through-hole 68d. In the illustrated example, three inclined holes 74 are formed, but the number of inclined holes 74 may be two or four or more. The inner diameter of the inclined holes 74 is smaller than the inner diameter of the central through-hole 68d. The centerline of the inclined holes 74 extends in a straight line. The circumferential position of the upstream opening 74a of the inclined hole 74 is positioned at a predetermined angle in a predetermined direction in the circumferential direction relative to the circumferential position of the downstream opening 74b (see Figure 3A). Also, the radial position of the downstream opening 74b of the inclined hole 74 is closer to the central axis C than the radial position of the upstream opening 74a (see Figure 3B). In this way, the inclined holes 74 are inclined to converge towards the central axis C while rotating around the center of the central axis C from the upstream opening 74a to the downstream opening 74b. Such inclined holes 74 generate an airflow that spirals and converges towards the center of the central axis C on the downstream side of the second flow path block 68.

[0065] Furthermore, in this embodiment, the inner diameter of the downstream opening 74b of the inclined hole 74 is smaller than the inner diameter of the upstream opening 74a. The inner diameter of the inclined hole 74 is tapered, gradually decreasing from the upstream opening 74a to the downstream opening 74b. Such an inclined hole 74 can increase the flow velocity of the injected compressed air by restricting the compressed air.

[0066] The air ejected from the inclined holes 74 creates a tornado-like flow downstream of the intake passage member 18F by spiral motion, converging near the central axis C and moving downstream. Such a tornado-like flow has strong directionality, and its flow direction is less likely to be disturbed. Therefore, the negative pressure generator 10G can efficiently direct the air flowing in from the intake passage 54 to the downstream side. Consequently, the negative pressure generator 10G of this embodiment can further improve the efficiency of compressed air utilization.

[0067] (Ninth Embodiment) As shown in Figure 13, the negative pressure generating device 10H of this embodiment includes an intake passage member 18H, a main body 20, an exhaust passage member 22, and a porous block 76. In the configuration of the negative pressure generating device 10H, components that are the same as those in the corresponding components of the negative pressure generating device 10 described with reference to Figures 2 to 5 are denoted by the same reference numerals and their detailed description is omitted.

[0068] The intake passage member 18H has a nozzle 78 that protrudes into the housing chamber 34 of the main body 20. A portion of the downstream side of the nozzle 78 has a conical section 79 that narrows in diameter toward the downstream side. Inside the intake passage member 18H, an intake passage 54 extends in the axial direction. The intake passage 54 opens at the downstream end 78b of the nozzle 78.

[0069] The outer surface 78a of the nozzle 78 is spaced inward from the inner surface 20a of the main body 20 that forms the containment chamber 34. A compressed air passage 50 is formed between the outer surface 78a of the nozzle 78 and the inner surface 20a of the main body 20. The negative pressure generating device 10H has an outlet 50a at the downstream end of the compressed air passage 50 that ejects compressed air toward the intake passage 54.

[0070] The porous block 76 is positioned adjacent to the upstream side of the nozzle 50a and blocks the compressed air passage 50. The porous block 76 fills the gap between the outer surface 78a of the nozzle 78 and the inner surface 20a of the main body 20. The porous block 76 is formed in a cylindrical shape that surrounds the nozzle 78. The downstream end 76a of the porous block 76 is positioned at the same axial position as the downstream end 78b of the nozzle 78 (intake passage member 18H).

[0071] The porous block 76 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 76 is not limited to a single layer of porous body, but may be composed of multiple porous bodies stacked together. Furthermore, the porous block 76 is not limited to a porous body, but may be replaced with a pseudo-porous structure formed by stacking multiple meshes (wire mesh) of a certain pitch in the thickness direction. In addition, the porous block 76 may be a structure composed of stacked metal plates with perforations formed on them. Moreover, the porous block 76 may be composed of a cage-like container of a predetermined shape filled with a large number of spheres or other fillers.

[0072] The negative pressure generator 10H of this embodiment rectifies the compressed air by homogenizing the flow of compressed air supplied from the supply channel 24a as it passes through the porous block 76, thereby suppressing energy loss due to turbulence in the compressed air. Furthermore, the porous block 76 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 76 reduces noise generated by the compressed air, maintaining a favorable working environment in the factory.

[0073] (Tenth Embodiment) As shown in Figure 14, the negative pressure generating device 10I of this embodiment has a second porous block 80 formed of a porous material. In the configuration of the negative pressure generating device 10I, components that are the same as those in the corresponding configurations of the negative pressure generating device 10 described with reference to Figures 2 to 5 and the negative pressure generating device 10H described with reference to Figure 13 are denoted by the same reference numerals and their detailed description is omitted.

[0074] As shown in Figure 14, the negative pressure generating device 10I of this embodiment includes an intake passage member 18I, a main body 20, an exhaust passage member 22, and a second porous block 80. The intake passage member 18I is a cylindrical member having a constant outer and inner diameter and extending in the axial direction. An intake passage 54 extending in the axial direction is formed inside the intake passage member 18I. The intake passage member 18I has a nozzle 78H protruding into the interior of the containment chamber 34.

[0075] The main body 20, exhaust flow path member 22, and supply port 24 are the same as those described with reference to Figures 2 to 5.

[0076] The second porous block 80 is positioned inside the reduced diameter portion 32. The second porous block 80 fills the gap between the outer surface 18a of the intake passage member 18I and the inner surface 20a of the main body portion 20. The cross-sectional area of ​​the second porous block 80 in a plane perpendicular to the axial direction decreases as it moves downstream in the axial direction.

[0077] The second porous block 80 is formed from a porous body created by sintering a large number of particles. Open pores that communicate with each other are formed between the particles constituting the second porous block 80. Compressed air can be circulated through the open pores in the second porous block 80 from the upstream side to the downstream side. In this embodiment, the diameter of the constituent particles (particle diameter) of the second porous block 80 gradually increases from the upstream side to the downstream side. Therefore, the pore diameter of the open pores formed between the constituent particles also gradually increases from the upstream side to the downstream side. Such a second porous block 80 can be manufactured, for example, by joining and integrating sintered body blocks with different particle diameters.

[0078] Other configurations of the second porous block 80, which are not limited to this example, are listed below. The second porous block 80 may be formed, for example, by stacking multiple metal meshes with different pitches. Alternatively, the second porous block 80 may be formed by stacking multiple punching plates with different pore diameters. Furthermore, the second porous block 80 may be formed by stacking multiple fillers (e.g., spheres) of different diameters in the axial direction inside a cage-like container of a predetermined shape.

[0079] The negative pressure generator 10I described above injects compressed air through the second porous block 80. This suppresses energy loss due to turbulence in the compressed air flow. Furthermore, the negative pressure generator 10I contributes to stabilizing the factory environment by suppressing heat generation from the compressed air through the cooling effect of the second porous block 80. In addition, the second porous block 80 improves the flow velocity of the injected compressed air. Since the second porous block 80 can adsorb foreign matter contained in the compressed air, it is suitable for use in clean environments. Therefore, the negative pressure generator 10I is suitable for stabilizing the factory environment.

[0080] With regard to the above embodiments, the following additional information is disclosed.

[0081] (Note 1) The negative pressure generating device (10, 10A, 10B, 10C, 10D, 10E, 10F, 10G) of the present disclosure comprises an intake passage (54) extending along a central axis (C), a compressed air passage (50) surrounding the intake passage in an annular manner, an exhaust passage (56) connected downstream of the intake passage and the compressed air passage, and a supply passage (24a) for supplying compressed air to the compressed air passage, wherein the compressed air passage is provided with a flow guide member (58) that guides the flow of the compressed air in a spiral shape around the central axis.

[0082] The negative pressure generating device described above can improve the efficiency of compressed air utilization.

[0083] (Note 2) In the negative pressure generating device described in Note 1, the flow guide member may include a flow path block (36, 68, 68G) 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 increase the efficiency of compressed air utilization by generating a spiral flow through the through holes.

[0084] (Note 3) The negative pressure generating device described in Note 2 may be an inclined hole (46, 74) such that the circumferential position of the upstream opening (46a, 74a) with respect to the central axis is different from the circumferential position of the downstream opening (46b, 74b) with respect to the central axis. This negative pressure generating device can generate a spiral flow downstream of the intake passage with a simple structure.

[0085] (Note 4) The negative pressure generating device described in Note 3, 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 has a simple structure and can generate a spiral flow downstream of the intake passage.

[0086] (Note 5) In the negative pressure generating device described in Note 3 or 4, 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 increase the flow velocity of the compressed air ejected from the inclined hole.

[0087] (Note 6) In the negative pressure generating device described in Note 2, the through hole may be a spiral hole (72) extending spirally around the central axis. This negative pressure generating device can generate a spiral flow downstream of the intake passage by injecting compressed air from the spiral hole.

[0088] (Note 7) In the negative pressure generating device described in Note 6, the inner diameter of the helical hole may gradually expand from the upstream opening (72a) to the downstream opening (72b).

[0089] (Note 8) In the negative pressure generating device described in Note 6 or 7, the flow path block may have a helical groove (72d) formed on the inner circumferential surface (72c) 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. This negative pressure generating device can further improve the utilization efficiency of compressed air by suppressing turbulence of the compressed air injected from the helical hole.

[0090] (Note 9) A negative pressure generating device according to any one of Notes 6 to 8, wherein the flow guide member is formed on the wall surface adjacent to the compressed air passage and has spiral irregularities (66) extending spirally around the central axis. This negative pressure generating device can generate a spiral flow downstream of the intake passage with a simple configuration, thereby increasing the efficiency of compressed air utilization.

[0091] (Note 10) A negative pressure generating device according to any one of Notes 1 to 9, wherein the supply passages may be provided in multiple locations spaced apart in the circumferential direction of the compressed air passage. This negative pressure generating device can increase the amount of compressed air supplied and the exhaust flow rate.

[0092] (Note 11) A negative pressure generating device (10H, 10I) in another aspect of the present disclosure comprises: an intake passage extending along a central axis; a compressed air passage encircling the intake passage in an annular manner; an exhaust passage connected downstream of the intake passage and the compressed air passage; a supply passage for supplying compressed air to the compressed air passage; and porous blocks (76, 80) arranged in the compressed air passage and having open holes for allowing the compressed air to pass through.

[0093] The negative pressure generator described above can rectify the flow of compressed air and suppress energy loss of the compressed air. In addition, the negative pressure generator contributes to stabilizing the factory environment by lowering the temperature of the compressed air, removing foreign matter from the compressed air, and suppressing noise.

[0094] (Note 12) In the negative pressure generating device described in Note 11, the pore diameter of the open pores in the porous block may gradually increase from upstream to downstream. This negative pressure generating device can improve the efficiency of compressed air utilization by improving the flow velocity of compressed air.

[0095] 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.

[0096] 10, 10A-10I... Negative pressure generator 24a... Supply channel 46, 74... Inclined hole 50... Compressed air channel 54... Intake channel 56... Exhaust channel 58... Flow guide member 72... Helical hole 72d... Helical groove 76, 80... Porous block

Claims

1. A negative pressure generating device (10, 10A, 10B, 10C, 10D, 10E, 10F, 10G) comprising: an intake passage (54) extending along a central axis (C); a compressed air passage (50) surrounding the intake passage in an annular shape; an exhaust passage (56) connected downstream of the intake passage and the compressed air passage; and a supply passage (24a) for supplying compressed air to the compressed air passage, wherein the compressed air passage is provided with a flow guide member (58) that guides the flow of the compressed air in a spiral shape around the central axis.

2. A negative pressure generating device according to claim 1, wherein the flow guide member comprises a flow path block (36, 68, 68G) arranged in the compressed air flow path and having a plurality of through holes formed therein for guiding the compressed air.

3. A negative pressure generating device according to claim 2, wherein the through holes are inclined holes (46, 74) that are inclined such that the circumferential position of the upstream opening (46a, 74a) with respect to the central axis and the circumferential position of the downstream opening (46b, 74b) with respect to the central axis are different.

4. A negative pressure generating device according to claim 3, wherein the inclined hole is further inclined such that the downstream opening approaches the central axis more closely than the upstream opening.

5. A negative pressure generating device according to claim 3, wherein the inclined hole has an inner diameter that gradually decreases from the upstream opening to the downstream opening.

6. A negative pressure generating device according to claim 2, wherein the through hole is a spiral hole (72) extending spirally around the central axis.

7. A negative pressure generating device according to claim 6, wherein the spiral hole has an inner diameter that gradually expands from the upstream opening (72a) to the downstream opening (72b).

8. A negative pressure generating device according to claim 6, wherein the flow path block has a helical groove (72d) formed on the inner circumferential surface (72c) 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.

9. A negative pressure generating device according to claim 6, wherein the flow guide member is formed on a wall surface adjacent to the compressed air passage and has spiral irregularities (66) extending spirally about the central axis.

10. A negative pressure generating device according to any one of claims 1 to 9, wherein the supply passages are provided in a plurality at intervals in the circumferential direction of the compressed air passage.

11. A negative pressure generating device (10H, 10I) comprising: an intake passage extending along a central axis; a compressed air passage encircling the intake passage in an annular shape; an exhaust passage connected downstream of the intake passage and the compressed air passage; a supply passage for supplying compressed air to the compressed air passage; and porous blocks (76, 80) arranged in the compressed air passage and having open holes for the passage of the compressed air.

12. A negative pressure generating device according to claim 11, wherein the porous block has a pore diameter that gradually increases from upstream to downstream.

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