Vacuum generation unit with silencer and silencer thereof

Abstract

[Problem] To provide a vacuum generation unit capable of reducing exhaust resistance of a silencer and suppressing the flow rate of compressed air required for generating negative pressure. [Solution] The vacuum generation unit 40 is provided between a manifold block 11 and a switching valve unit 30 and generates negative pressure using compressed air supplied through the switching valve unit 30, the vacuum generation unit comprising: a casing 41 including a first air supply port 42, an ejector part 50, a first negative pressure output port 43, and an exhaust port 44; and a silencer 70 provided to the exhaust port. The silencer has a silencing part 71 comprising a silencing flow passage 72 composed of a silencing material 73, and an exhaust part 80 that discharges exhaust gas silenced by the silencing part to the atmosphere. An exhaust space 82 that is connected to an outlet opening of the silencing flow passage, and an exhaust flow passage 83 that causes the exhaust space to communicate with the outside are formed in an exhaust body of the exhaust part. The flow passage cross-sectional area of the exhaust space is larger than that of the outlet opening, and the exhaust space is formed in a vertically long shape in which the height is greater than the width.

Description

Vacuum generating unit with a silencer and its silencer

[0001] The present invention relates to a vacuum generating unit that is attached intervening between a manifold block having an air supply passage and a switching valve unit, and generates a negative pressure by compressed air supplied from the air supply passage through the switching valve unit, particularly to one having a silencer at an exhaust port, and its silencer.

[0002] A vacuum generating unit that is attached intervening between a manifold block having an air supply passage and a switching valve unit, and generates a negative pressure by compressed air supplied from the air supply passage through the switching valve unit is already known as disclosed in Patent Document 1.

[0003] By the way, the vacuum generating unit described in Patent Document 1 has an exhaust port for exhausting the compressed air used for generating the vacuum to the outside, and a silencer is attached to the exhaust port to suppress the exhaust sound. However, there is a concern that as the exhaust resistance due to the silencer increases, the consumption amount of compressed air required to generate the necessary negative pressure increases, and a countermeasure is desired from the viewpoint of energy saving.

[0004] Japanese Patent Application Laid-Open No. 2012-215173

[0005] Therefore, the technical problem of the present invention is to suppress the consumption amount of compressed air required to generate the necessary negative pressure by reducing the exhaust resistance due to the silencer attached to the exhaust port as much as possible in a vacuum generating unit that is attached intervening between a manifold block having an air supply passage and a switching valve unit, and generates a negative pressure by compressed air supplied from the air supply passage through the switching valve unit, and to provide such a silencer.

[0006] To solve the above problems, the present invention provides a vacuum generating unit interposed between a manifold block having an air intake passage and a switching valve unit, for generating negative pressure by compressed air supplied from the air intake passage through the switching valve unit, the vacuum generating unit having an air intake port for introducing the compressed air from the switching valve unit, an ejector section for generating negative pressure with the compressed air, an output port for outputting the negative pressure, an exhaust port for discharging exhaust from the ejector section to the outside, and a silencer attached to the exhaust port, the silencer having one end and the other end at both ends in the axial direction, and comprising a sound-dampening section located on the one end side and an exhaust section located on the other end side of the sound-dampening section, the sound-dampening section The exhaust unit has a sound-absorbing channel that penetrates in the axial direction, with one end connected to the exhaust port and the other end having an outlet opening, and a sound-absorbing material provided in the sound-absorbing channel. The exhaust unit has an exhaust body connected to the other end of the sound-absorbing unit, and within the exhaust body there is an exhaust space extending in the axial direction with an inlet opening connected to the outlet opening, and an exhaust channel that connects the exhaust space to the outside. The cross-sectional area of ​​the channel in the exhaust space is formed to be larger than the opening area of ​​the outlet opening, and the exhaust body is formed to be elongated vertically, with the height dimension being greater than the width dimension in a cross section perpendicular to the axial direction, and the cross-sectional area of ​​the channel in the exhaust space is also formed to be elongated vertically, with the height dimension being greater than the width dimension.

[0007] In the vacuum generating unit with silencer, preferably, the exhaust passage is formed from an upper exhaust passage extending upward from the exhaust space and a lower exhaust passage extending downward, and on the outer circumferential surface of the exhaust body around the axis, one opening of the upper exhaust passage is opened upward as an upper external exhaust port, and one opening of the lower exhaust passage is opened downward as a lower external exhaust port. In this case, more preferably, the outer circumferential surface of the exhaust body is formed of a pair of flat surfaces extending vertically parallel to each other at both ends in the width direction straddling the axis, an upper curved surface that is convex upward and connects the upper edges of the pair of flat surfaces, and a lower curved surface that is convex downward and connects the lower edges of the pair of flat surfaces, the upper external exhaust port is opened on the upper curved surface around the axis from at least one upper edge of the pair of flat surfaces, and the lower external exhaust port is opened on the lower curved surface around the axis from at least one lower edge of the pair of flat surfaces.

[0008] Preferably, the other opening of the upper exhaust passage is provided as an upper inner exhaust port at the upper part of the inner circumferential surface of the exhaust space, and the other opening of the lower exhaust passage is provided as a lower inner exhaust port at the lower part of the inner circumferential surface, with the upper outer exhaust port being formed to be the same as or larger than the opening area of ​​the upper inner exhaust port, and the lower outer exhaust port being the same as or larger than the opening area of ​​the lower inner exhaust port. Furthermore, more preferably, the sound-absorbing material has a cylindrical shape in which the sound-absorbing passage is formed by through holes penetrating in the axial direction, and the sum of the opening areas of the lower and upper inner exhaust ports of the exhaust passage is formed to be the same as or larger than the opening area of ​​the outlet opening in the sound-absorbing passage.

[0009] Preferably, the sound-absorbing section has a sound-absorbing body connected to the exhaust port, the sound-absorbing body having an outer wall with an open end on the other end and a hollow interior, a connecting portion provided on one end of the outer wall and connected to the exhaust port, a cylindrical housing portion inside the outer wall that extends from one end to the other end and accommodates the sound-absorbing material in a removable manner, a communication passage formed in the connecting portion that connects the exhaust port and the sound-absorbing passage, and a space formed radially outward of the housing portion and the sound-absorbing material, wherein, with the sound-absorbing material housed in the housing portion, the other end of the sound-absorbing material protrudes from the other end edge of the housing portion, exposing its outer circumferential surface to the space. More preferably, the sound-absorbing material is housed in the housing portion with its one end in contact with the bottom of the housing portion and its other end in contact with the end face of one end of the exhaust body.

[0010] Preferably, the outer surface of the sound-absorbing body and the outer surface of the exhaust body are formed on the same plane along the axis. Furthermore, the above problem can be solved by the silencer used in the vacuum generation unit.

[0011] As described above, according to the vacuum generation unit with silencer and the silencer of the present invention, in the silencer attached to the exhaust port of the vacuum generation unit, the flow path cross-sectional area of ​​the exhaust space is made larger than the opening area of ​​the outlet opening of the sound-dampening flow path, and the flow path cross-section of the exhaust space is made vertically elongated with a height dimension greater than the width dimension. As a result, the exhaust resistance by the silencer can be reduced as much as possible, and the amount of compressed air consumed to generate the necessary negative pressure can be suppressed.

[0012] This is an external perspective view of a connected assembly including a vacuum generating unit according to one embodiment of the present invention. This is an exploded perspective view of the connected assembly in Figure 1. This is an exploded perspective view of a vacuum generating device. This is a plan view of a vacuum generating unit with a silencer according to the present invention. This is a rear view of the vacuum generating unit with a silencer. This is a longitudinal cross-sectional view showing the vacuum generating device in a state where a vacuum (negative pressure) is being generated. This is a longitudinal cross-sectional view showing the vacuum generating device in a state where the vacuum (negative pressure) is being broken. This is a perspective view of the silencer. This is an exploded perspective view of the silencer. This is a side view of the silencer. This is a longitudinal cross-sectional view of the silencer. This is a cross-sectional view of the silencer taken along the line XII-XII in Figure 10. This is a cross-sectional view of the silencer taken along the line XIII-XIII in Figure 10. This is a cross-sectional view of the silencer taken along the line XVI-XVI in Figure 11.

[0013] Hereinafter, an embodiment of the vacuum generation unit according to the present invention will be described with reference to the attached drawings. Figure 1 is an external perspective view of a connected assembly 1 comprising a vacuum generation device 10 including a vacuum generation unit 40 according to one embodiment of the present invention, Figure 2 is an exploded perspective view of the connected assembly 1, and Figure 3 is an exploded perspective view of the vacuum generation device 10. As shown in Figures 2 and 3, the vacuum generation unit 40 is interposed and installed between a manifold block 11 and a switching valve unit 30, and the vacuum generation device 10 is formed by sequentially stacking these manifold block 11, vacuum generation unit 40 and switching valve unit 30 from bottom to top and connecting them to each other. As shown in Figures 1 and 2, the connected assembly 1 is formed by arranging a plurality of vacuum generators 10, 10 (two in this embodiment) side by side in the horizontal direction (width direction), with a port block 2 and an end block 6 on one side in the width direction (left side in the figure), and a port block 4 on the opposite side in the width direction (right side in the figure), and then integrating these by butting their sides together. In other words, the vacuum generation unit 40 constitutes a part of the connected assembly 1. For example, a switching valve device in which a switching valve unit 30 is directly stacked on a manifold block 11 may be mixed in and arranged side by side with the vacuum generators 10.

[0014] The end block 6 has a flat front surface 7 at its front end in the front-rear direction perpendicular to the width direction, and a plurality of connectors 7a are provided on this front surface 7, spaced apart in the vertical direction. These connectors 7a are configured to supply power and electrical signals to a pilot valve 31 provided in the switching valve unit 30 of the vacuum generator 10.

[0015] As shown in Figure 2, the port blocks 2 and 4, like the end block 6, have planar front surfaces 3 and 5 at their front ends, and supply ports 3a and 5a and discharge ports 3b and 5b are provided on each of these front surfaces 3 and 5, spaced apart in the vertical direction. Inside each port block 2 and 4, there is an air intake hole 4a, a first exhaust hole 4b, and a second exhaust hole 4c extending in the width direction. For example, when compressed air is supplied from the supply port 5a of one port block 4, the compressed air is supplied through the air intake hole 4a to the air intake hole 13 that penetrates the width direction of each manifold block 11. Conversely, when compressed air is supplied from the supply port 3a of the other port block 2, the compressed air is supplied through the air intake hole 4a of the other port block 2 to the air intake hole 13 of each manifold block 11. If there are many connected vacuum generators, etc., compressed air may be supplied from both the port blocks 2 and 4 at both ends.

[0016] The discharge port 5b of port block 4 communicates with the first and second exhaust holes 14 and 15, which are installed through the width direction of each manifold block 11, via the first and second exhaust holes 4b and 4c. Similarly, the discharge port 3b of port block 2 also communicates with the first and second exhaust holes 14 and 15 of each manifold block 11, via the first and second exhaust holes 4b and 4c.

[0017] Next, the vacuum generator 10 will be described with reference to Figures 3 and 6. As shown in Figure 3, the manifold block 11 has a base body 12, which is the body of the manifold block 11. The base body 12 has an air intake hole 13, a first exhaust hole 14 and a second exhaust hole 15, a first negative pressure port 16 and a second negative pressure port 17. Specifically, the base body 12 is formed in the shape of a rectangular parallelepiped extending in the front-rear direction, and a flat front surface 12a is formed at the front end of the base body 12. The first negative pressure port 16 and the second negative pressure port 17 are opened on this front surface 12a with a vertical gap between them, and the first and second negative pressure ports 16 and 17, respectively, communicate with a first negative pressure passage 18 and a second negative pressure passage 19 formed inside the base body 12, as shown in Figure 6. These first and second negative pressure passages 18 and 19 are connected to a first negative pressure input port 20 and a second negative pressure input port 21 opened on the upper end surface 12b of the base body 12. In this embodiment, a plug member 22 is inserted into the second negative pressure port 17, and the second negative pressure port 17 is airtightly closed.

[0018] The first exhaust port 14, the intake port 13, and the second exhaust port 15 are arranged inside the base body 12 with a gap between them in the front-rear direction and penetrate the base body 12 in the width direction. Compressed air supplied from the intake port 13 is supplied to the switching valve unit 30 through the vacuum generation unit 40. The first and second exhaust ports 14 and 15 exhaust the compressed air exhausted from the switching valve unit 30 through the vacuum generation unit 40. The base body 12 has a planar upper end surface 12b that extends in the front-rear direction at its top, and a first exhaust input port 23, a first negative pressure input port 20, a first intake output port 24, a second negative pressure input port 21, and a second exhaust input port 25 are sequentially opened on this upper end surface 12b from the rear to the front.

[0019] Next, the switching valve unit 30 will be described. As shown in Figures 3 and 6, the switching valve unit 30 is a pilot-operated two-position switching valve and has a configuration as a five-port valve. The switching valve unit 30 has a valve body 32 that extends in the front-rear direction. The valve body 32 is formed by having a main body 33 having five ports EA, A, P, B, and EB, a piston cover 36 and a pilot valve section 37 connected to the rear end of the main body 33, and an end cap 38 connected to the front end of the main body 33.

[0020] The five ports EA, A, P, B, and EB are located on the lower end surface 32a of the main body 33, with the intake port P located in the center in the front-rear direction, the first output port A and the second output port B located on both sides of the intake port P in the front-rear direction, the first discharge port EA located closer to the piston cover 36 than the first output port A, and the second discharge port EB located closer to the end cap 38 than the second output port B.

[0021] Inside the main body 33, a valve hole 33a, through which five ports EA, A, P, B, and EB communicate, runs along the front-rear direction, and a spool 34 is slidably inserted into the valve hole 33a in the front-rear direction. The spool 34 is formed so that its front-rear length is slightly shorter than that of the valve hole 33a, and a piston 36b, which is slidably housed in a piston chamber 36a, is provided at the rear end of the spool 34 so as to move toward and away from the rear end surface of the spool 34. The front end of the spool 34 is constantly biased toward the rear, i.e., toward the piston 36b, by compressed air supplied into the end cap 38 from the air intake port P.

[0022] The longitudinal cross-sectional area of ​​the piston chamber 36a, that is, the pressure-receiving area of ​​the piston 36b, is larger than the pressure-receiving area of ​​the front end surface of the spool 34. Therefore, when pilot air is supplied to the piston chamber 36a, the piston 36b pushes the spool 34 forward (towards the end cap 38) and displaces it against the biasing force of the compressed air acting on the front end surface of the spool 34. As a result, compressed air is supplied to the vacuum generation unit 40 through the first output port A, and negative pressure is output from the vacuum generation unit 40. In this embodiment, the air supply inlet port P and the first output port A are in communication, the second output port B and the second discharge port EB are in communication, and the first discharge port EA is sealed airtight by blocking communication with the other ports P, A, B, and EB (see Figure 6).

[0023] On the other hand, when pilot air is not supplied to the piston chamber 36a, the spool 34 is displaced to the rear by the biasing force of the compressed air supplied into the end cap 28. As a result, the negative pressure output from the vacuum generation unit 40 is stopped, and the vacuum is broken as the negative pressure is released by atmospheric pressure. In this embodiment, the air supply inlet port P and the second output port B are in communication, the first output port A and the first discharge port EA are in communication, and the second discharge port EB is sealed airtight by blocking communication with the other ports EA, P, A, and B (see Figure 7).

[0024] The pilot valve section 37 is provided with an electromagnetic solenoid type pilot valve 31 connected to the air intake port P. This pilot valve 31 communicates with the piston chamber 36a through the pilot passage 37a and supplies and discharges pilot air to the piston chamber 36a.

[0025] Next, the vacuum generation unit 40 will be described with reference to Figures 3-7. The vacuum generation unit 40 has a casing 41 that houses an ejector unit 50 that generates negative pressure using compressed air. The outer surface of the casing 41 has a first air supply port 42 for introducing compressed air from the switching valve unit 30 to the ejector unit 50, a first negative pressure output port 43 and a second negative pressure output port 60 for outputting the negative pressure generated in the ejector unit 50, and an exhaust port 44 for discharging exhaust from the ejector unit 50 to the outside. A silencer 70 for suppressing exhaust noise is attached to the exhaust port 44.

[0026] Specifically, the casing 41 is elongated, with a depth greater than its width, and vertically elongated, with a height greater than its width. The casing 41 has a first mounting surface 41a extending upward, which is planar, for fixedly mounting the valve body 32 of the switching valve unit 30, and a second mounting surface 41b extending downward, which is planar, for fixedly mounting the base body 12 of the manifold block 11. Inside the casing 41, there is an internal space through which the first air supply port 42, the first negative pressure output port 43, the second negative pressure output port 60, and the exhaust port 44 are all connected. The first air supply port 42 is located on the first mounting surface 41a, and the first negative pressure output port 43 and the second negative pressure output port 60 are located on the second mounting surface 41b.

[0027] The ejector unit 50 has a nozzle unit 51 and a diffuser unit 52. The nozzle unit 51 is provided in the internal space of the casing 41 between the first air supply port 42, the first negative pressure output port 43 and the second negative pressure output port 60. Compressed air supplied from the first air supply port 42 is ejected through the nozzle unit 51 to the diffuser unit 52, thereby supplying negative pressure to the first negative pressure port 16 and the second negative pressure port 17 through the first negative pressure output port 43 and the second negative pressure output port 60.

[0028] The diffuser section 52 is located within the casing 41, downstream (front) of the nozzle section 51. Specifically, an air supply passage 45 communicating with the first air supply port 42 is connected to the upstream end (rear end) of the nozzle section 51. The diffuser section 52 communicating with the exhaust port 44 is coaxially connected to the downstream end (front end) of the nozzle section 51, and a first output passage 46 (see Figure 7) communicating with the first negative pressure output port 43 and a second output passage 53 communicating with the second negative pressure output port 60 are also connected to it.

[0029] Then, when compressed air supplied from the first air supply port 42 is ejected from the nozzle section 51 at a flow velocity exceeding the speed of sound toward the diffuser section 52, according to Bernoulli's principle, air is drawn into the diffuser section 52 through the first and second negative pressure ports 16 and 17 and the first and second negative pressure output ports 43 and 60. At the same time, the drawn-in air, along with the compressed air ejected from the nozzle section 51, is discharged as exhaust from the diffuser section 52 through the exhaust port 44 to the outside. As a result, negative pressure can be supplied to the first and second negative pressure ports 16 and 17. In this embodiment, as described above, the second negative pressure port 17 is hermetically sealed, so no negative pressure is output from the second negative pressure port 17.

[0030] As shown in Figures 6 and 7, the casing 41 is provided with a supply passage 47, a first exhaust passage 48, and a second exhaust passage 49 that penetrate between the first mounting surface 41a and the second mounting surface 41b, and the first and second output passages 46 and 53 that merge with each other and are connected to the ejector section 50. The supply passage 47 is for supplying compressed air from the air intake hole 13 to the switching valve unit 30. One end of the supply passage 47 is opened on the second mounting surface 41b as an air intake input port 54, and the other end of the supply passage 47 is opened on the first mounting surface 41a as a second air intake output port 55. The air intake input port 54 is connected to the first air intake output port 24 of the manifold block 11, and the second air intake output port 55 is connected to the air intake inlet port P of the switching valve unit 30.

[0031] The first exhaust passage 48 is for exhausting air flowing out of the first discharge port EA of the switching valve unit 30 through the first exhaust hole 14. One end of the first exhaust passage 48 is opened on the second mounting surface 41b as the first exhaust outlet port 56, and the other end of the first exhaust passage 48 is opened on the first mounting surface 41a as the first exhaust inlet port 57. The first exhaust outlet port 56 is connected to the first exhaust input port 23 of the manifold block 11, and the first exhaust inlet port 57 is connected to the first discharge port EA of the switching valve unit 30. However, in this embodiment, as will be described later, this passage 48 is used as a passage for introducing air when the vacuum is broken.

[0032] The second exhaust passage 49 is for exhausting air flowing out of the second discharge port EB of the switching valve unit 30 through the second exhaust hole 15. One end of the second exhaust passage 49 is opened on the second mounting surface 41b as a second exhaust outlet port 58, and the other end of the second exhaust passage 49 is opened on the first mounting surface 41a as a second exhaust inlet port 59. The second exhaust outlet port 58 is connected to the second exhaust input port 25 of the manifold block 11, and the second exhaust inlet port 59 is connected to the second discharge port EB of the switching valve unit 30.

[0033] The first negative pressure output port 43 of the first output passage 46 and the second negative pressure output port 60 of the second output passage 53 are provided on the second mounting surface 41b. The first negative pressure output port 43 is connected to the first negative pressure input port 20 of the first negative pressure passage 18, and the second negative pressure output port 60 is connected to the second negative pressure input port 21 of the second negative pressure passage 19. A second air supply port 61 is provided on the first mounting surface 41a, but in this embodiment, the second air supply port 61 is hermetically sealed within the casing 41 and is therefore not connected to any of the passages described above that are formed within the casing 41.

[0034] In the vacuum generator 10, which includes the vacuum generation unit 40 configured in this way, when the pilot valve 31 of the switching valve unit 30 is energized and pilot air is supplied to the piston chamber 36a, the first output port A is connected to the air supply inlet port P and the second output port B is connected to the second discharge port EB. Then, as shown in Figure 6, compressed air from the air supply hole 13 of the manifold block 11 is supplied to the ejector section 50 of the vacuum generation unit 40 through the switching valve unit 30, and the vacuum generator 10 enters a negative pressure generation state. The negative pressure generated in the ejector section 50 is output from the first negative pressure port 16, and for example, a workpiece can be attracted by a suction pad connected to the first negative pressure port 16. At this time, the air drawn in from the first negative pressure port 16 by the negative pressure is, as described above, exhausted together with the compressed air used to generate the negative pressure in the ejector section 50 and released to the outside through the exhaust port 44 from the diffuser section 52. In this embodiment, as described above, no negative pressure is output from the second negative pressure port 17.

[0035] On the other hand, in this negative pressure generation state, when the power supply to the pilot valve 31 is stopped, and the pilot air in the piston chamber 36a is exhausted, the first output port A is connected to the first discharge port EA and the second output port B is connected to the supply air inlet port P. As a result, the generation of negative pressure by the ejector unit 50 is stopped, and as shown in Figure 7, the first negative pressure port 16 is connected to the atmosphere from the ejector unit 50 through the exhaust port 44. At the same time, the first negative pressure port 16 is connected to the atmosphere from the ejector unit 50 through the first discharge port EA of the switching valve unit, the first exhaust hole 14 of the manifold block 11, and the discharge ports 3b and 5b of the port blocks 2 and 4 in sequence. As a result, the vacuum generator 10 is switched from a negative pressure generation state to a vacuum release state, which can, for example, break the negative pressure on the suction pad holding the workpiece and release the workpiece from the suction pad. In this embodiment, the compressed air supplied to the second air supply port 61 through the second output port B of the switching valve unit 30 is not used for vacuum generation or even vacuum breaking, as the second air supply port 61 is blocked as described above.

[0036] By the way, when the vacuum generator 10 is in the negative pressure state, it generates a loud exhaust noise when it discharges the exhaust from the ejector section 50 through the exhaust port 44. Therefore, in order to suppress this exhaust noise, the vacuum generator unit 40 is configured to discharge the exhaust from the ejector section 50 to the outside through the silencer 70 attached to the exhaust port 44.

[0037] As shown in Figures 6 and 8-14, the silencer 70 has one end 70a and the other end 70b at both ends in the front-rear direction (axis L direction), and comprises a sound-dampening section 71 located on the side of the one end 70a and an exhaust section 80 located on the other end side of the sound-dampening section 71. The sound-dampening section 71 has a sound-dampening passage 72 that penetrates in the axis L direction, with one end 70a communicating with the exhaust port 44 and the other end 70b having an outlet opening 72a, and a sound-dampening material 73 provided in the sound-dampening passage 72.

[0038] Specifically, the sound-absorbing section 71 has a sound-absorbing body 74 connected to the exhaust port 44. The sound-absorbing body 74 has an outer wall 75 with an open end on the other end 70b and a hollow interior, and a connecting portion 76 provided on one end 70a of the outer wall 75 and connected to the exhaust port 44 of the vacuum generating unit 40. Inside the outer wall 75, there is a cylindrical housing portion 77 that extends from the one end 70a to the other end 70b and houses a sound-absorbing material 73 that can be inserted and removed, and a space portion 79 formed radially outside the sound-absorbing channel 72, the housing portion 77, and the sound-absorbing material 73. At this time, the length of the housing portion 77 in the axial direction L is shorter than the length of the space portion 79 in the axial direction L, and the space portion 79 is partitioned by the inner surface of the outer wall 75 and the outer circumferential surfaces of the housing portion 77 and the sound-absorbing material 73. As will be described later, in this embodiment, the sound-absorbing channel 72 is formed by a through hole that penetrates the sound-absorbing material 73 in the axial direction L.

[0039] The outer wall 75 is formed in a cylindrical shape with an open end 70b and a closed end 70a. The outer surface of the outer wall 75 is formed from a pair of flat surfaces 75a, 75a that are parallel to each other and extend vertically at both ends in the width direction on either side of the axis L, an upper curved surface 75b that is convex upward and connects the upper edges of the pair of flat surfaces 75a, 75a, and a lower curved surface 75c that is convex downward and connects the lower edges of the pair of flat surfaces 75a, 75a. In other words, the outer shape of the outer wall 75 is formed symmetrically in the vertical and width directions on either side of the axis L in a cross section perpendicular to the axis L, and is a vertically elongated shape in which the height dimension is greater than the width dimension, specifically an oval shape (track shape) that extends vertically. Furthermore, the distance between the pair of flat surfaces 75a, 75a is equal to or slightly smaller than the distance between the pair of side surfaces 41c (see Figure 4) on both sides in the width direction of the casing 41, in particular, the width dimension of the front end surface of the casing 41 in which the exhaust port 44 is formed.

[0040] The connecting portion 76 protrudes coaxially with the axis L from the end (bottom surface) of one end 70a of the outer wall 75 and is inserted into the recess 41d of the exhaust port 44 so as to be removable. The communication passage 78 is provided through the connecting portion 76 in the direction of the axis L, and this communication passage 78 is formed to have a uniform longitudinal cross-sectional area (flow passage cross-sectional area) throughout and communicates with the diffuser portion 52 through the exhaust port 44. A ring-shaped sealing member 76a is attached to the outer circumferential surface of the connecting portion 76 to ensure airtightness with the recess 41d.

[0041] The housing portion 77 has a hollow projection 77a that protrudes from the bottom of the outer wall 75 toward the other end 70b in the axial direction L, and an insertion hole 77b that penetrates the inside of the projection 77a in the axial direction L and into which the sound-absorbing material 73 is fitted. The outer shape of the projection 77a is formed in the shape of a rectangular parallelepiped, and both sides of the projection 77a in the width direction of the shorter side are connected to the inner surface of the outer wall 75 around the axis L (the inner surface of the pair of flat surfaces 75a, 75a). On the other hand, the space portion 79 is formed between the upper and lower sides 77c, 77c of the projection 77a in the vertical direction and the inner surfaces of the upper curved surface 75b and lower curved surface 75c of the outer wall 75. Furthermore, as described above, the edge (tip) of the projection 77a toward the other end 70b is located toward the one end 70a side than the edge (tip) of the outer wall 75 toward the other end 70b. In other words, the tip of the protruding portion 77a is located on the bottom side of the tip of the outer wall 75 in the direction of the axis L. When the sound-absorbing material 73 is housed in the housing portion 77, the other end 70b of the sound-absorbing material 73 (the tip portion) protrudes from the tip of the housing portion 77, and its outer circumferential surface around the axis L is exposed to the space portion 79.

[0042] The sound-absorbing material 73 has a through-hole that penetrates in the axial direction L and forms the sound-absorbing passage 72. The sound-absorbing passage 72 is formed to have a substantially uniform longitudinal cross-sectional area (passage cross-sectional area) from the opening at one end 70a to the opening at the other end 70b, and the opening at the other end 70b forms the outlet opening 72a. Furthermore, the longitudinal cross-sectional area (passage cross-sectional area) of this sound-absorbing passage 72 is the same as, or preferably larger than, the longitudinal cross-sectional area (passage cross-sectional area) of the communication passage 78. Specifically, the sound-absorbing material 73 is formed in a hollow cylindrical shape and is housed in the housing 77 with its end at one end 70a in contact with the bottom of the housing 77 and its end at the other end 70b in contact with the end face at one end 70a of the exhaust body 81. For this reason, the sound-absorbing material 73 is positioned within the silencer 70 in the radial direction and the axial direction L. The sound-absorbing material 73 is formed from, for example, urethane foam or felt.

[0043] As shown in Figures 9 and 11, the exhaust section 80 has an exhaust body 81 connected to the other end 7b side (the side of the outlet opening 72a of the sound-dampening passage 72) of the sound-dampening section 71. Inside the exhaust body 81, there is an exhaust space 82 having an inlet opening 82a connected to the outlet opening 72a of the sound-dampening passage 72, and exhaust passages 83 and 88 that connect the exhaust space 82 to the outside. The outer shape of the exhaust body 81 is vertically elongated in a cross-section perpendicular to the axis L direction, where the height dimension is greater than the width dimension.

[0044] Specifically, the outer peripheral surface of the exhaust body 81 around the axis L is, similarly to the silencing body 74, formed by a pair of flat surfaces 84, 84 that are parallel to each other and extend in the vertical direction at both side ends in the width direction sandwiching the axis L, an upper curved surface 85 that is convex upward and connects the upper end edges of the pair of flat surfaces 84, 84, and a lower curved surface 86 that is convex downward and connects the lower end edges of the pair of flat surfaces 84, 84. In the present embodiment, both the upper and lower curved surfaces 85, 86 are formed by arc surfaces. The center of the arc of the upper curved surface 85 is arranged between the axis L and the upper end edges of the pair of flat surfaces 84, 84 in the vertical direction, and the center of the arc of the lower curved surface 86 is arranged between the axis L and the lower end edges of the pair of flat surfaces 84, 84 in the vertical direction. That is, the central angles of the upper and lower curved surfaces 85, 86 are formed in a fan shape smaller than 180 degrees.

[0045] And, the cross-section of the exhaust body 81 orthogonal to the direction of the axis L is formed in an elongated oval shape (track shape) that is symmetric in the vertical and width directions sandwiching the axis L. The outer peripheral surface of the exhaust body 81 around the axis L is formed on the same surface along the axis L as the outer peripheral surface of the silencing body 74 around the axis L (that is, they are flush along the axis L). That is, also in this exhaust body 81, the distance between the pair of flat surfaces 84, 84 is equal to or slightly smaller than the distance between the pair of side surfaces 41c (see FIG. 4) on both sides in the width direction of the casing 41, particularly, the width dimension of the front end surface where the exhaust port 44 is formed in the casing 41.

[0046] The exhaust space 82, like the exhaust body 81, is formed in a vertically elongated shape, with its height greater than its width. That is, the exhaust space 82 is formed in a vertically elongated oval shape (track shape) that is symmetrical in the vertical and width directions with respect to the axis L. Specifically, as shown in Figures 11 and 14, the exhaust space 82 is formed within the exhaust body 81, partitioned by a pair of parallel flat surfaces 82b, 82b extending vertically, an upper curved surface 82c with an upward recess, and a lower curved surface 82d with a downward recess. In this embodiment, both the upper and lower curved surfaces 82c and 82d are formed by arcuate surfaces. At the end of the exhaust space 82 on the side of one end 70a, an expanding portion 82e is formed that gradually widens the vertical cross-section toward the inlet opening 82a.

[0047] The maximum width of the inlet opening 82a of the exhaust space 82 is the same as the maximum width (i.e., diameter) of the outlet opening 72a of the sound-absorbing channel 72 formed in the sound-absorbing material 73. With both ends of the inlet opening 82a in the width direction aligned with both ends of the outlet opening 72a in the width direction, the end face on the other end 70b of the sound-absorbing material 73 abuts against the end face on the one end 70a of the exhaust body 81. The longitudinal cross-sectional area (channel cross-sectional area) at all points along the axis L in the exhaust space 82, including the inlet opening 82a, is formed to be larger than the opening area (channel area) of the outlet opening 72a.

[0048] As shown in FIGS. 9, 12, and 13, one end of the exhaust flow paths 83 and 88 opens as upper and lower exhaust ports 83a and 88a on the outer peripheral surface around the axis L of the exhaust body 81. The exhaust flow paths 83 and 88 are formed by an upper exhaust flow path 83 extending upward from the exhaust space 82 and a lower exhaust flow path 88 extending downward. One opening of the upper exhaust flow path 83 is opened upward as the upper exhaust port 83a on the outer peripheral surface around the axis L of the exhaust body 81. Also, one opening of the lower exhaust flow path 88 is opened downward as the lower exhaust port 88a. Specifically, the upper exhaust port 83a is opened in the upper curved surface 85, and the lower exhaust port 88a is opened in the lower curved surface 86. More specifically, the upper exhaust port 83a is opened in the upper curved surface 85 around the axis L from the upper end edges of the pair of flat surfaces 82b and 82b, and the lower exhaust port 88a is opened in the lower curved surface 86 around the axis L from the lower end edges of the pair of flat surfaces 82b and 82b. Note that the upper and lower exhaust ports 83a and 88a do not necessarily need to be opened from both the upper and lower end edges of the pair of flat surfaces 82b. For example, they may be opened from one upper and lower end edge to the middle of the upper and lower curved surfaces 85 and 86. Also, the exhaust flow path and the exhaust port do not necessarily need to be formed by a through-hole penetrating the outer peripheral surface of the exhaust body 81 (i.e., in a direction orthogonal to the axis L) as in the present embodiment. For example, they may be formed by a through-hole penetrating along the axis L in the end wall on the other end 70b side of the exhaust body 81 facing the inlet opening 82a.

[0049] Furthermore, in the present embodiment, the upper and lower exhaust ports 83a and 88a are divided into two by ribs 87 and 87 extending inward (toward the exhaust space 82) from the circumferential center portions of the upper and lower curved surfaces 86 and 82d in the vertical direction of the exhaust body 81. That is, the upper and lower exhaust ports 83a and 88a are formed by being divided into a total of four, two each in the upper and lower parts, in the upper curved surface 82c and the lower curved surface 82d by the ribs 87 and 87 formed on the center line extending in the vertical direction through the axis L.

[0050] On the other hand, as shown in Figures 13 and 14, the other opening of the upper exhaust passage 83 is opened as an upper inner exhaust port 83b, straddling the flat surface 82b and the upper curved surface 82c that partition the exhaust space 82, above the vertical axis L. Similarly, the other opening of the lower exhaust passage 88 is opened as a lower inner exhaust port 88b, straddling the flat surface 82b and the lower curved surface 82d, below the vertical axis L. Specifically, the upper and lower inner exhaust ports 83b and 88b open around axis L at the other end 70b side of the exhaust space 82, from the pair of flat surfaces 82b, 82b to the upper and lower curved surfaces 82c, 82d, respectively, and to the upper and lower pair of ribs 87, 87. In other words, the upper and lower internal exhaust ports 83b and 88b are also formed in the same way as the upper and lower external exhaust ports 83a and 88a, with a total of four ports, two at the top and two at the bottom.

[0051] Here, the upper and lower exhaust passages 83 and 88 are formed such that the sum of the cross-sectional areas of the passages is the same, or preferably increases, from the upper and lower inner exhaust ports 83b and 88b toward the upper and lower outer exhaust ports 83a and 88a. In this embodiment, the opening area of ​​each of the four outer exhaust ports 83a and 88a is the same, or preferably larger, than the opening area of ​​the corresponding four inner exhaust ports 83b and 88b. Furthermore, the combined opening area of ​​the four inner exhaust ports 83b and 88b is the same, or preferably larger, than the opening area of ​​the outlet opening 72a of the sound-absorbing material 73.

[0052] Next, the operation of the vacuum generation unit 40 with silencer 70 will be explained with reference to Figures 6 and 13. As shown in Figure 6, when the switching valve unit 30 is switched to a negative pressure generation state, compressed air supplied to the vacuum generation unit 40 is ejected from the nozzle section 51 toward the diffuser section 52, and consequently, air connected to the first negative pressure port 16 is drawn in from the first negative pressure output port 43, generating negative pressure. At that time, the exhaust noise generated by the discharge of exhaust from the exhaust port 44 is suppressed by the silencer 70. The exhaust, with its noise suppressed, is then discharged to the outside through the exhaust space 82 and exhaust passages 83 and 88 shown in Figure 13, and out through the external exhaust ports 83a and 88a.

[0053] Here, the exhaust body 81 is formed in a vertically elongated shape, with its height greater than its width, and the flow path cross-section of the exhaust space 82 is also formed in a vertically elongated shape, with its height greater than its width, thus enabling the securing of a larger exhaust space 82. For this reason, the vertical cross-sectional area (flow path cross-sectional area) of the exhaust space 82, including the inlet opening 82a, can be made larger than the opening area of ​​the outlet opening 72a of the sound-absorbing flow path 72. Furthermore, the sum of the flow path cross-sectional areas at each of the four exhaust flow paths 83 and 88 can be made larger than the opening area of ​​the outlet opening 72a of the sound-absorbing material 73. In this way, the flow velocity of the silencing exhaust released from the outlet opening 72a of the sound-absorbing flow path 72 can be reduced in the exhaust space before being discharged to the outside through the exhaust flow paths 83 and 88. As a result, the pressure loss of the compressed air flowing through the silencer 70 can be suppressed, and stable exhaust to the outside can be achieved. Consequently, the amount of compressed air consumed to generate the necessary negative pressure in the vacuum generator 10 can be suppressed.

[0054] Furthermore, as shown in Figure 1, even when the vacuum generating units 40 of the vacuum generating device 10 are arranged adjacent to each other in the connected assembly 1, the upper and lower external exhaust ports 83a and 88a face upward and downward, respectively, so that the exhaust from the silencer 70 does not interfere with each other and increase exhaust resistance. At the same time, even if the width of the vacuum generating device 10 is reduced, the exhaust body and exhaust space are formed in a vertically elongated shape, so that exhaust resistance can be suppressed as described above, and the consumption of compressed air can be reduced.

[0055] 11 Manifold block 13 Air intake port (air intake passage) 30 Switching valve unit 40 Vacuum generation unit 41 Casing 42 First air intake port (air intake port) 43 First negative pressure output port (output port) 44 Exhaust port 50 Ejector section 60 Second negative pressure output port (output port) 70 Silencer 70a One end 70b Other end 71 Sound-absorbing section 72 Sound-absorbing passage 72a Outlet opening 73 Sound-absorbing material 73a Through hole 74 Sound-absorbing body 75 Outer wall 76 Connection section 77 Housing section 78 Communication passage 79 Space section 80 Exhaust section 81 Exhaust body 82 Exhaust space 82a Inlet opening 83 Upper exhaust passage 83a Upper outer exhaust port 83b Upper inner exhaust port 84 Flat surface 85 Upper curved surface 86 Lower curved surface 87 Rib 88 Lower exhaust passage 88a Lower outer exhaust port 88b Lower inner exhaust port L axis

Claims

1. A vacuum generating unit interposed between a manifold block having an air intake passage and a switching valve unit, for generating negative pressure by compressed air supplied from the air intake passage through the switching valve unit, wherein the vacuum generating unit has an air intake port for introducing the compressed air from the switching valve unit, an ejector section for generating negative pressure by the compressed air, an output port for outputting the negative pressure, an exhaust port for discharging exhaust from the ejector section to the outside, and a silencer attached to the exhaust port, wherein the silencer has one end and the other end at both ends in the axial direction, and comprises a sound-absorbing section located at the one end and an exhaust section located at the other end than the sound-absorbing section, wherein the sound-absorbing section has a sound-absorbing passage that penetrates in the axial direction, with one end connected to the exhaust port and the other end having an outlet opening, and a sound-absorbing material provided in the sound-absorbing passage, The vacuum generating unit with a silencer is characterized in that the exhaust section has an exhaust body connected to the other end of the sound-dampening section, and within the exhaust body there is an exhaust space extending in the axial direction with an inlet opening connected to the outlet opening, and an exhaust flow path that connects the exhaust space to the outside, the cross-sectional area of ​​the flow path in the exhaust space is formed to be larger than the opening area of ​​the outlet opening, the exhaust body is formed to be elongated vertically in a cross section perpendicular to the axial direction, with the height dimension being greater than the width dimension, and the cross-sectional area of ​​the flow path in the exhaust space is also formed to be elongated vertically with the height dimension being greater than the width dimension.

2. The vacuum generating unit with a silencer according to claim 1, characterized in that the exhaust passage is formed from an upper exhaust passage extending upward from the exhaust space and a lower exhaust passage extending downward, and on the outer circumferential surface of the exhaust body around the axis, one opening of the upper exhaust passage is opened upward as an upper outer exhaust port, and one opening of the lower exhaust passage is opened downward as a lower outer exhaust port.

3. The vacuum generating unit with silencer according to claim 2, characterized in that the outer circumferential surface of the exhaust body is formed from a pair of flat surfaces extending vertically parallel to each other at both ends in the width direction straddling the axis, an upper curved surface convex upward and connecting the upper edges of the pair of flat surfaces, and a lower curved surface convex downward and connecting the lower edges of the pair of flat surfaces, the upper external exhaust port is opened on the upper curved surface around the axis from at least one upper edge of the pair of flat surfaces, and the lower external exhaust port is opened on the lower curved surface around the axis from at least one lower edge of the pair of flat surfaces.

4. The vacuum generating unit with a silencer according to claim 3, characterized in that the other opening of the upper exhaust passage is provided as an upper inner exhaust port at the upper part of the inner circumferential surface of the exhaust space, the other opening of the lower exhaust passage is provided as a lower inner exhaust port at the lower part of the inner circumferential surface, the upper outer exhaust port is formed to be the same as or larger than the opening area of ​​the upper inner exhaust port, and the lower outer exhaust port is formed to be the same as or larger than the opening area of ​​the lower inner exhaust port.

5. The sound-absorbing material has a cylindrical shape that forms the sound-absorbing channel through through holes penetrating in the axial direction, and the sum of the opening areas of the lower and upper inner exhaust ports of the exhaust channel is formed to be the same as or larger than the opening area of ​​the outlet opening in the sound-absorbing channel, as described in 4.

6. The sound-absorbing section has a sound-absorbing body connected to the exhaust port, the sound-absorbing body having an outer wall with an open end on the other end and a hollow interior, a connecting section provided on one end of the outer wall and connected to the exhaust port, a cylindrical housing section inside the outer wall that extends from one end to the other end and accommodates the sound-absorbing material in a removable manner, a communication passage formed in the connecting section that connects the exhaust port and the sound-absorbing passage, and a space formed radially outward of the housing section and the sound-absorbing material, the vacuum generating unit with silencer according to claim 5, wherein, with the sound-absorbing material housed in the housing section, the other end of the sound-absorbing material protrudes from the other end edge of the housing section, exposing its outer surface to the space.

7. The vacuum generating unit with silencer according to claim 6, characterized in that the sound-absorbing material is housed in the housing such that one end of the material abuts against the bottom of the housing and the other end of the material abuts against the end face of one end of the exhaust body.

8. The vacuum generating unit with a silencer according to claim 6, characterized in that the outer surface of the sound-dampening body and the outer surface of the exhaust body are formed on the same plane along the axis.

9. The silencer used in the vacuum generating unit according to claim 1.

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