Attractor Car

Abstract

To provide a suction vehicle capable of suppressing occurrence of cavitation along with an increase in temperature of sealing water in a vacuum pump to preferably maintain a negative pressure of a receiver tank and improve workability.SOLUTION: A suction vehicle including a receiver tank 5 and a water sealing type vacuum pump 25 includes: a suction tube path that communicates with the receiver tank 5; a drive air intake tube path 200 capable of taking air therein; an ejector 100 in which the suction tube path is connected to a suction air connection port 103, the drive air intake tube path 200 is connected to a drive air connection port 101, and a suction port 25a of the water sealing type vacuum pump 25 communicates with a discharge port 102; a bypass tube path 300 that causes a portion of the suction tube path in a further upstream side than the ejector 100 and the suction port 25a to communicate each other; and a check valve 400 provided in the bypass tube path 300 so as to, while allowing a flow of air from the receiver tank 5 side to the suction port 25a side, prevent air from reversely flowing from the suction port 25a side to the receiver tank 5 side.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a suction vehicle that uses a vacuum pump to pressurize and depressurize a receiver tank that collects objects to be collected. [Background technology]

[0002] Suction trucks have been widely used at construction sites, sewage treatment plants, etc., and use vacuum pumps to reduce the pressure in a receiver tank, guiding sludge, earth and sand, waste liquid, and other materials to be collected into the receiver tank, and then transporting the collected materials to the treatment plant. These suction trucks use two types of vacuum pumps, Roots type and water-sealed type, depending on the situation.

[0003] A Roots-type vacuum pump has two two- or three-blade rotors housed within a casing, which rotate in opposite directions at the same frequency. The rotors and the casing rotate without contact, maintaining a small gap. This allows the volume enclosed by the two rotor blades and the inner wall of the casing to be transported from the suction port to the discharge port, generating negative pressure. Roots-type vacuum pumps have advantages such as low cost, the ability to operate with a small amount of sealed water, and low power. Vehicle-mounted suction devices and suction vehicles equipped with Roots-type vacuum pumps have been developed with various designs (see, for example, Patent Document 1). The suction device disclosed in Patent Document 1 includes multiple Roots-type vacuum pumps connected in series and a wet dust collection tank that collects dust particles in the gas that has passed through the Roots-type vacuum pumps. A cooling water inlet path is provided to introduce water from the wet dust collection tank into the upstream Roots-type vacuum pump.

[0004] On the other hand, a water ring vacuum pump has a structure as shown in Figure 8. In the water ring vacuum pump 500 shown in Figure 8, water is placed in a cylindrical casing 501. When the impeller 502 is rotated eccentrically, the enclosed water 506 is forced against the inner cylindrical wall of the casing 501 by centrifugal force, forming a water return flow 503, creating a crescent-shaped space on its inner periphery. In this space, an independent air chamber formed by two adjacent blades and the inner surface of the water return flow 503 repeatedly expands and contracts as the impeller 502 rotates. By opening a suction port 504 and a discharge port 505 at appropriate locations on the side of this air chamber, the water return flow 503 can function as a piston, enabling continuous rotation of a reciprocating suction machine. In other words, the water ring vacuum pump 500 generates negative pressure by rotating water in a circular motion. Because water forms part of the pump, it offers many advantages, including quiet operation, no metal contact, and no need for oil. In addition, since there is a large gap between the casing 501 and the impeller 502, it is resistant to foreign matter, and furthermore, since it no longer functions as a pump when the water runs out, it is less likely to seize.

[0005] Various structures of vehicle-mounted suction devices and suction vehicles equipped with water-sealed vacuum pumps have been developed in the past (see, for example, Patent Document 2). The suction vehicle disclosed in Patent Document 2 is equipped with a receiver tank (hopper) mounted on the vehicle body for suctioning and collecting objects to be collected, a dust collector that purifies the dirty air flowing from the receiver tank, a water-sealed vacuum pump that forms a wet dust collection tank that captures fine dust sucked in together with the air from the dust collector with sealed water, and a silencer that removes dust and reduces noise from the air that flows through the water-sealed vacuum pump. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-132942 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-237906 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the above-mentioned vacuum pump, frictional heat generated between the casing and the sealed water, as well as heat generated by increased pump load, especially in the high vacuum range, gradually increases the temperature of the sealed water, increasing the amount of vapor in the sealed water and making cavitation more likely. Furthermore, as the vacuum pump reaches a high vacuum range, the amount of vapor in the sealed water increases, making cavitation more likely. This cavitation is one factor that makes it difficult to steadily maintain negative pressure in the receiver tank, especially in the high vacuum range. Meanwhile, there is a strong market demand for maintaining good negative pressure in the high vacuum range and improving workability using a suction truck. This problem is particularly pronounced in water-sealed vacuum pumps, which require a large amount of sealed water.

[0008] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a suction vehicle that can suppress the occurrence of cavitation caused by an increase in the temperature of the water sealed in the vacuum pump, thereby maintaining a good negative pressure in the receiver tank, thereby improving workability. [Means for solving the problem]

[0009] A suction vehicle according to a first aspect of the present invention is a suction vehicle equipped with a receiver tank for collecting materials to be collected and a vacuum pump for pressurizing and depressurizing the receiver tank, and is further equipped with a suction line that can communicate with the receiver tank, a drive air intake line that is capable of taking in air at atmospheric pressure or a pressure higher than atmospheric pressure, an ejector to which the suction line is connected a suction air connection port and the drive air intake line is connected to a drive air connection port, and whose suction port is connected to a discharge port, a bypass line that connects the upstream side of the ejector on the suction line with the suction port of the vacuum pump, and a check valve provided in the bypass line to allow air to flow from the receiver tank side to the suction port of the vacuum pump while preventing air from flowing back from the suction port of the vacuum pump to the receiver tank side.

[0010] In the suction vehicle according to the first aspect of the present invention, when the driving air of the ejector is introduced near the suction port of the vacuum pump and expands, the temperature of the air drops as the pressure drops, thereby lowering the temperature of the water sealed in the vacuum pump. Furthermore, the driving air has a higher pressure than the area near the suction port of the vacuum pump, which has reached a high vacuum due to the reduced pressure, and this prevents the negative pressure near the suction port from becoming too high. This helps to suppress the occurrence of cavitation.

[0011] Furthermore, when the receiver tank begins to be depressurized, the upstream side of the bypass line's check valve becomes higher pressure than the downstream side of the bypass line's check valve, causing the check valve to open and air in the receiver tank to be sucked into the vacuum pump primarily through the bypass line. This allows the large amount of air present in the receiver tank at the start of depressurization to be quickly sent to the vacuum pump, allowing the pressure in the receiver tank to quickly reach a high vacuum. Furthermore, once the receiver tank reaches a certain level of vacuum, the difference between the pressure of the drive air introduced by the ejector and the air pressure in the receiver tank, which becomes negatively pressurized higher than the drive air pressure, increases. As a result, the pressure upstream of the bypass line's check valve becomes lower (negative pressure increases) than the downstream side of the bypass line's check valve, causing the check valve to close. Air in the receiver tank is sucked into the vacuum pump along with the drive air taken in from the drive air intake line, but only through the ejector. This allows the large amount of air present in the receiver tank to be quickly expelled to the outside when the receiver tank begins to be depressurized, while once the vacuum level in the receiver tank has increased to a certain level, the effect of suppressing cavitation by the driving air introduced by the ejector can be maximized, allowing for efficient suction work.

[0012] Furthermore, according to the suction vehicle of the first aspect of the present invention, a check valve without an actuator-driven mechanism is used, and the above-mentioned bypass pipeline can be opened and closed automatically with accurate timing based on the change in the pressure difference between the upstream and downstream sides of the check valve, which changes when the receiver tank starts to be depressurized and when the vacuum level in the receiver tank has increased to a certain level.

[0013] A suction vehicle according to a second aspect of the present invention is the suction vehicle according to the first aspect, wherein the check valve is a swing-type check valve having a hinge and a valve body attached so as to be freely swingable via the hinge.

[0014] A third aspect of the present invention is a suction vehicle according to the first or second aspect, wherein a silencer is installed at the intake and exhaust port through which air is exhausted when the receiver tank is depressurized by operation of the vacuum pump to silence the exhaust noise, and the drive air intake pipe includes a first drive air intake pipe, a second drive air intake pipe, and a confluence pipe where the downstream side of the first drive air intake pipe and the downstream side of the second drive air intake pipe join and are connected to the drive air connection port of the ejector, and the upstream side of the first drive air intake pipe is positioned so that moisture produced in the silencer can be sucked in together with atmospheric air.

[0015] A suction vehicle according to a fourth aspect of the present invention is a suction vehicle according to any one of the first to third aspects, which is provided with a four-way switching valve that can be switched between a suction switching state that connects the suction port of the vacuum pump to the receiver tank and connects the discharge port of the vacuum pump to the intake and exhaust ports, and a pressurization switching state that connects the discharge port of the vacuum pump to the receiver tank and connects the suction port of the vacuum pump to the intake and exhaust ports, and the ejector and the bypass pipeline are provided between the four-way switching valve and the suction port of the vacuum pump.

[0016] A suction vehicle according to a fifth aspect of the present invention is a suction vehicle according to the first or second aspect, wherein the drive air intake pipeline has a first drive air intake pipeline, a second drive air intake pipeline, and a confluence pipeline in which the downstream side of the first drive air intake pipeline and the downstream side of the second drive air intake pipeline join and are connected to the drive air connection port of the ejector, and a manual valve with an adjustable opening is provided on the upstream side of the second drive air intake pipeline, and the manual valve is provided adjacent to an operation panel that is operated when pressurizing or depressurizing the receiver tank. [Effects of the Invention]

[0017] According to the present invention, it is possible to maintain a good negative pressure in the receiver tank while suppressing the occurrence of cavitation caused by an increase in the temperature of the water sealed in the vacuum pump. Furthermore, when the pressure in the receiver tank starts to be reduced, the air present in the receiver tank is quickly discharged to the outside, and once the degree of vacuum in the receiver tank has increased to a certain level, the effect of suppressing cavitation by the driving air introduced by the ejector can be maximized. This makes it possible to provide a suction vehicle that can improve workability. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a side view of a suction vehicle according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the suction vehicle according to the embodiment of the present invention. [Figure 3] 1. FIG. 4 is a diagram showing the air flow when the receiver tank in the suction vehicle in FIG. 1 is depressurized. [Figure 4] 1. FIG. 4 is a diagram showing the air flow when pressurizing the receiver tank in the suction vehicle of FIG. [Figure 5] 5 is an explanatory diagram of a drive air intake pipe, a bypass pipe, and a check valve shown in FIGS. 3 and 4. FIG. [Figure 6] 6A and 6B are diagrams showing the check valve of FIG. 5, in which FIG. 6A is a front view of the check valve, and FIG. 6B is a cross-sectional view taken along line AA of FIG. 5A. [Figure 7]6 is a diagram showing an operating lever and an operating panel used to adjust the opening of the drive air intake pipe of FIG. 5. FIG. [Figure 8] FIG. 2 is a schematic diagram for explaining the operation of a water ring vacuum pump. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of the present invention will be described below with reference to the accompanying drawings. As shown in FIGS. 1 and 2, a suction device 2 is mounted on a subframe 4 on a chassis 3 of a suction vehicle 1. Specifically, a receiver tank 5 for collecting sludge, earth and sand, waste liquid, and other materials to be collected is mounted on the rear of the subframe 4. The receiver tank 5 includes, for example, a tank body 5a having a circular cross-section and a rear-end opening, and a tailgate 5c for opening and closing the rear-end opening. The tailgate 5c is pivotally supported, for example, via a hinge pin 5b at the upper rear end of the tank body 5a. An opening / closing cylinder 5d is provided between the tank body 5a and the tailgate 5c. By extending and retracting the opening / closing cylinder 5d, the tailgate 5c can open and close the rear-end opening of the tank body 5a. At the bottom of the tailgate 5c, there are provided a suction port 8 with an on-off valve which serves as a suction port for objects to be collected, and a discharge port 9 with an on-off valve which serves as a discharge port for objects to be collected.

[0020] The receiver tank 5 is pivotally supported on the subframe 4 via a tilting shaft 10 provided at the rear of the subframe 4 so that it can tilt. A tilting cylinder 11 is provided between the subframe 4 and the receiver tank 5, and by extending or contracting the tilting cylinder 11, the receiver tank 5 can be rotated upright or down around the tilting shaft 10.

[0021] When the suction device 2 sucks and collects the objects to be collected into the receiver tank 5, it reduces the pressure inside the receiver tank 5 and sucks the objects to be collected into the receiver tank 5 from the outside through a suction hose (not shown) connected to the suction port 8. On the other hand, when the suction device 2 discharges the objects to be collected inside the receiver tank 5 to, for example, a sludge treatment plant, it pressurizes the inside of the receiver tank 5 and discharges the objects to be collected inside the receiver tank 5 to the outside through a discharge hose (not shown) connected to the discharge port 9. It is also possible to discharge the objects to be collected inside the receiver tank 5 by opening the tailgate 5c and rotating the receiver tank 5 upright.

[0022] Additionally, a water ring vacuum pump 25 (Fig. 2) is provided on the subframe 4 between the operator's cab 13 and the receiver tank 5 to pressurize and depressurize the inside of the receiver tank 5 and generate an air flow. Although not shown in detail, the water ring vacuum pump 25 is driven to rotate by the driving force of an engine (not shown) connected via a drive shaft of the PTO (power take-off) of the suction vehicle 1. Around this water ring vacuum pump 25 are arranged pipes connected to the water ring vacuum pump 25, various valves, an operation panel 15 to be operated when pressurizing and depressurizing the receiver tank 5, and the like.

[0023] As shown in Figures 3 and 4, the suction device 2 includes a receiver tank 5 as a primary catcher, secondary catchers 20 and tertiary catchers 21 each consisting of a cyclone, a quaternary catcher 22 consisting of an air-water separator and water tank, an air-switched four-way valve 24 (hereinafter referred to as the "four-way switching valve"), an ejector 100, a water-sealed vacuum pump 25, and other components connected via piping made of a metal round steel pipe or the like to enable pressurization and depressurization of the receiver tank 5. In this embodiment, the tertiary catcher 21, the quaternary catcher 22, and a silencer 23 incorporating an intake and exhaust port are integrally provided. These components are connected via receiver tank pressurization and depressurization piping 7. The intake and exhaust port functions as an exhaust port when the receiver tank 5 is depressurized, and as an intake port when the receiver tank 5 is pressurized.

[0024] The receiver tank 5 and the secondary catcher 20 are connected by a first pipe 7a, the secondary catcher 20 and the tertiary catcher 21 are connected by a second pipe 7b, the tertiary catcher 21 and the first port a of the four-way switching valve 24 are connected by a third pipe 7c, the second port b of the four-way switching valve 24 and the suction air connection port 103 of the ejector 100 are connected by a fourth pipe 7d, the quaternary catcher 22 and the third port c of the four-way switching valve 24 are connected by a fifth pipe 7e, and the silencer 23 and the fourth port d of the four-way switching valve 24 are connected by a sixth pipe 7f. In addition, a bypass pipe 300 is provided that branches from the fourth pipe 7d and is connected to the suction port 25a of the water ring vacuum pump 25. In addition, the bypass pipe 300 and the discharge port 102 of the ejector 100 are connected by an eighth pipe 7h. The ejector 100 can be made using known technology, having a drive air connection port 101 that takes in drive air, a discharge port 102 that discharges the drive air taken in from the drive air connection port 101, and a suction air connection port 103 that sucks in the air to be sucked in (air in the receiver tank 5) by utilizing the pressure drop caused inside by the flow of drive air.

[0025] To reduce the pressure in the receiver tank 5, the four-way switching valve 24 is switched to the suction switching state and the water ring vacuum pump 25 is driven. When the four-way switching valve 24 is switched to the suction switching state, the first port a and the second port b are connected, and the third port c and the fourth port d are connected. 3, an air flow is formed from the receiver tank 5 to the first pipe 7a to the secondary catcher 20 to the second pipe 7b to the tertiary catcher 21 to the third pipe 7c to the four-way selector valve 24 to the fourth pipe 7d to the ejector 100, the eighth pipe 7h and the bypass line 300 to the suction port 25a of the water ring vacuum pump 25, and also from the discharge port 25b of the water ring vacuum pump 25 to the seventh pipe 7g to the fourth catcher 22 to the four-way selector valve 24 to the silencer 23 (the intake and exhaust port contained in the silencer 23), and the air in the receiver tank 5 is exhausted from the silencer 23. This gradually reduces the pressure inside the receiver tank.

[0026] On the other hand, when pressurizing the receiver tank 5, the four-way switching valve 24 is switched to the pressurization switching state and the water ring vacuum pump 25 is driven. When the four-way switching valve 24 is switched to the pressurization switching state, the first port a and the third port c are connected, and the second port b and the fourth port d are connected. 4, an air flow is formed from the discharge port 25b of the water ring vacuum pump 25 → the seventh pipe 7g → the fourth catcher 22 → the fifth pipe 7e → the four-way selector valve 24 → the third pipe 7c → the tertiary catcher 21 → the second pipe 7b → the secondary catcher 20 → the first pipe 7a → the receiver tank 5, and also from the silencer 23 (the intake and exhaust port contained in the silencer 23) → the sixth pipe 7f → the four-way selector valve 24 → the fourth pipe 7d → the ejector 100, the eighth pipe 7h and the bypass line 300 → the suction port 25a of the water ring vacuum pump 25. As a result, air taken in from the silencer 23 is sent to the receiver tank 5, and the inside of the receiver tank 5 is gradually pressurized.

[0027] That is, by switching the four-way switching valve 24 to the suction switching state, the suction port 25a of the water ring vacuum pump 25 is connected to the receiver tank 5, and the discharge port 25b of the water ring vacuum pump 25 is connected to the silencer 23. On the other hand, by switching the four-way switching valve 24 to the pressurization switching state, the discharge port 25b of the water ring vacuum pump 25 is connected to the receiver tank 5, and the suction port 25a of the water ring vacuum pump 25 is connected to the silencer 23.

[0028] The ejector 100 and the bypass pipe 300 are provided between the four-way switching valve 24 and the suction port 25a of the water ring vacuum pump 25, so that the direction of air flowing through the ejector 100 and the bypass pipe 300 can be made the same regardless of whether the four-way switching valve 24 is in the suction switching state or the pressurization switching state.

[0029] 3 to 5, the suction device 2 includes a first drive air intake pipe 201, a second drive air intake pipe 202, and a junction pipe 203. The first drive air intake pipe 201 has an air intake port at a position inside the silencer 23 where water tends to collect, and is capable of sucking in the water that has collected inside the silencer 23 together with the air.

[0030] 1 and 7, the second drive air intake conduit 202 has an air intake port 202a located adjacent to the operation panel 15 that is operated when pressurizing or depressurizing the receiver tank 5. A manual valve 204 with an adjustable opening is provided near the air intake port 202a of the second drive air intake conduit 202, and an operation lever 204a for operating the manual valve 204 is disposed adjacent to the operation panel 15.

[0031] The confluence pipe 203 is a pipe formed by the confluence of the downstream side of the first drive air intake pipe 201 and the downstream side of the second drive air intake pipe 202, and the downstream side of this confluence pipe 203 is connected to the drive air connection port 101 of the ejector 100.

[0032] 5, the bypass pipe 300 corresponds to the range indicated by the symbol A. The bypass pipe 300 connects the fourth pipe 7d, which is located upstream of the ejector 100, with the suction port 25a of the water ring vacuum pump 25. The bypass pipe 300 has a first bypass pipe 301 that extends vertically downward from the upstream side and then turns horizontally, and a second bypass pipe 302 that extends vertically upward from the downstream side and then turns horizontally, and the downstream end of the first bypass pipe 301 and the upstream end of the second bypass pipe 302 are flange-joined to each other. The joined first bypass pipe 301 and second bypass pipe 302 form a substantially S-shape.

[0033] The bypass pipe 300 has a pipe diameter significantly larger than the air passage inside the ejector 100, and the flow path resistance is significantly smaller than that inside the ejector 100. The pipe diameter of the second bypass pipe 302 is larger than the pipe diameter of the first bypass pipe 301, and the first bypass pipe 301 and the second bypass pipe 302 are aligned so that their inner bottom surfaces coincide with each other. Therefore, as shown in FIG. 5 , the center line C1 of the first bypass pipe 301 and the center line C2 of the second bypass pipe 302 are vertically shifted from each other.

[0034] A check valve 400 is provided between the downstream end of the first bypass pipe 301 and the upstream end of the second bypass pipe 302, which are both oriented horizontally (hereinafter also referred to as the "horizontal portion of the bypass pipeline 300"). In this embodiment, a swing-type check valve having a hinge 402 and a valve element 403 attached so as to be swingable via the hinge 402 is provided as the check valve 400. As shown in FIGS. 6( a) and 6(b), for example, the swing-type check valve has an annular valve seat 401, the hinge 402 attached to the upper part of the valve seat 401, and a disk-shaped valve element 403 pivotally supported so as to be swingable via the hinge 402. The disk-shaped valve element 403 hangs down due to its own weight so that the line connecting its tip and the hinge 402 is oriented vertically. The swing-type check valve 400 is disposed with the main surface of the valve seat 401 facing vertically so that the valve element 403 is in a closed state when facing vertically.

[0035] The check valve 400 has a peripheral edge of a valve seat 401 sandwiched between a flange 301a of the first bypass pipe 301 and a flange 302a of the second bypass pipe 302. A valve element 403 of the check valve 400 opens when air flows from the receiver tank 5 toward the suction port 25a of the water ring vacuum pump 25, and closes the pipe when air flows from the suction port 25a of the water ring vacuum pump 25 toward the receiver tank 5. In other words, the check valve 400 allows air to flow from the receiver tank 5 toward the suction port 25a of the water ring vacuum pump 25, while preventing air from flowing back from the suction port 25a of the water ring vacuum pump 25 toward the receiver tank 5. As shown in FIG. 6(a), a center line C3 of the opening of the valve seat 401 is located below a center line C2 of the second bypass pipe 302.

[0036] In addition, ring-shaped sealing materials are interposed between the valve seat 401 and the flange portion 301a of the first bypass pipe 301, and between the valve seat 401 and the flange portion 302a of the second bypass pipe 302, to prevent air leakage.

[0037] Next, the operation of the suction device 2 will be described.

[0038] First, with the suction vehicle 1 stopped, a PTO (power take-off) switch provided in the driver's cab 13 or the like is turned on. Then, the driving force of the vehicle's engine is supplied to the water ring vacuum pump 25.

[0039] Next, to start suction, the operator presses suction button 15a on operation panel 15. This switches four-way selector valve 24 as shown in Figure 3, and together with the operation of water ring vacuum pump 25, air in receiver tank 5 is sucked into water ring vacuum pump 25 via first pipe 7a, secondary catcher 20, second pipe 7b, tertiary catcher 21, third pipe 7c, four-way selector valve 24, fourth pipe 7d, and bypass pipeline 300 (ejector 100 and eighth pipe 7h). As a result, the object to be collected is sucked and collected into receiver tank 5 through a suction hose and suction port 8 (not shown).

[0040] The air sucked into the water ring vacuum pump 25 is discharged from the discharge port 25b and exhausted to the outside via the quaternary catcher 22, the four-way switching valve 24, and the silencer 23 (the intake and exhaust port contained within the silencer 23).

[0041] To switch from the suction switching state to the neutral switching state, the operator presses the neutral button 15b on the operation panel 15. This switches the four-way switching valve 24 to the neutral switching state. To switch from the neutral switching state to the pressurizing switching state, the operator presses the pressurizing button 15c on the operation panel 15. This switches the four-way switching valve 24 to the pressurizing switching state.

[0042] When depressurization of the receiver tank 5 begins, a large amount of air is sucked from the receiver tank 5 and is sucked into the ejector 100 via the first pipe 7a, the secondary catcher 20, the second pipe 7b, the tertiary catcher 21, the third pipe 7c, the four-way switching valve 24, and the fourth pipe 7d. At the same time, because the flow resistance of the bypass pipe 300 is significantly smaller than that of the ejector 100, the valve element 403 of the check valve 400 is pushed open by air flowing from the receiver tank 5 side, which is the high-pressure side, to the suction port 25a side of the water ring vacuum pump 25, which is the low-pressure side. As a result, most of the air sucked into the water ring vacuum pump 25 passes through the bypass pipe 300. In this way, after the receiver tank 5 starts to be depressurized, a large amount of air is sucked from the receiver tank 5 through the bypass line 300 that bypasses the ejector 100 until the negative pressure inside the receiver tank 5 increases sufficiently, allowing the pressure inside the receiver tank 5 to quickly reach a high vacuum range.

[0043] After that, when the negative pressure in the receiver tank 5 increases to a certain level, the amount of air sucked into the water ring vacuum pump 25 decreases, and the valve element 403 of the check valve 400 can no longer be forced open by the flowing air. As a result, all of the air sucked into the water ring vacuum pump 25 passes only through the ejector 100. The ejector 100 acts to increase the negative pressure on the fourth pipe 7d side by taking in driving air, so the negative pressure on the fourth pipe 7d and the first bypass pipe 301 increases. Conversely, the eighth pipe 7h side, which has taken in driving air, acts to decrease the negative pressure, so the negative pressure on the eighth pipe 7h and the second bypass pipe 302 decreases. Therefore, the second bypass pipe 302 side becomes higher in pressure than the first bypass pipe 301 side, and the valve element 403 of the check valve 400 is subjected to a greater force to close.

[0044] As the negative pressure in the receiver tank 5 increases, the load on the water ring vacuum pump 25 increases, causing more heat to be generated and making it easier for the temperature of the water sealed in the water ring vacuum pump 25 to rise. Furthermore, as the negative pressure increases, the water sealed in becomes more likely to evaporate, making it easier for cavitation to occur. In this embodiment, these problems are solved by the action of the ejector 100, which will be described later.

[0045] That is, since the ejector 100 is connected not only to the suction line that is connected to the receiver tank 5 but also to the drive air intake line 200, the outside air at atmospheric pressure taken in from the first drive air intake line 201 and the second drive air intake line 202 also passes through the ejector 100 and is sucked into the suction port 25a of the water ring vacuum pump 25.

[0046] Because the temperature of the outside air is lower than that of the sealed water inside the water ring vacuum pump 25, when the outside air is taken into the water ring vacuum pump 25, the temperature of the sealed water drops. Furthermore, when the outside air is introduced near the suction port 25a of the water ring vacuum pump 25, it expands and its pressure drops, which lowers the temperature of the outside air and therefore the temperature of the sealed water in the water ring vacuum pump 25. Furthermore, when the outside air is taken into the water ring vacuum pump 25, the air pressure inside the water ring vacuum pump 25 increases. Therefore, it is possible to effectively suppress cavitation caused by the rise in the temperature of the sealed water and the drop in air pressure inside the water ring vacuum pump 25, and to maintain a good negative pressure in the receiver tank 5.

[0047] In addition, the water accumulated in the silencer 23 is also sent to the water ring vacuum pump 25 through the first drive air intake line 201 of the drive air intake line 200, so that the sealed water that is lost as the water ring vacuum pump 25 operates can be replenished and the temperature of the sealed water can be lowered.

[0048] In addition to the effects described above, the suction vehicle 1 described above also provides the effects described below.

[0049] Because check valve 400 is a swing-type check valve having a swingable valve element 403 pivotally supported on hinge 402, the opening and closing operation of bypass pipe 300 described above is performed automatically and with accurate timing based on the change in the pressure difference between the upstream and downstream sides of check valve 400, which changes when pressure reduction in receiver tank 5 begins and when the negative pressure in receiver tank 5 has increased to a certain level. Furthermore, swing-type check valves have a simple configuration, and are less expensive and less prone to malfunction than systems that control air flow externally.

[0050] Furthermore, since the ejector 100 and the bypass pipe 300 are provided between the four-way switching valve 24 and the suction port 25a of the water ring vacuum pump 25, the direction of air flowing through the ejector 100 and the bypass pipe 300 can be made the same whether the four-way switching valve 24 is in the suction switching state or the pressurization switching state. This eliminates the need to change the orientation of the check valve 400 provided in the bypass pipe 300 between the suction switching state and the pressurization switching state.

[0051] Furthermore, the second bypass pipe 302 provided downstream of the check valve 400 has a larger pipe diameter than the first bypass pipe 301 provided upstream of the check valve 400, and is therefore less likely to interfere with the operation of the valve element 403 of the check valve 400. This allows for a greater variety of usable check valves.

[0052] Furthermore, since the manual valve 204 is provided in the second drive air intake conduit 202, adjusting the manual valve 204 to the closed side increases the flow rate of air sucked into the water ring vacuum pump 25 through the bypass conduit 300, thereby increasing the flow rate of air sucked from inside the receiver tank 5. On the other hand, adjusting the manual valve 204 to the open side increases the flow rate of air sucked into the water ring vacuum pump 25 through the second drive air intake conduit 202, thereby suppressing cavitation and increasing the negative pressure in the receiver tank 5.

[0053] Furthermore, since the operating lever 204a for operating the manual valve 204 is provided near the operating panel 15, the above adjustment can be made while watching the operating panel 15, improving workability.

[0054] Although one embodiment of the suction vehicle according to the present invention has been described above, the specific configuration is not limited to this embodiment.

[0055] For example, in this embodiment, an example has been shown in which a swing-type check valve is used as the check valve 400, but a lift-type check valve having a valve element that slides in a direction perpendicular to the air flow may also be used. Also, in this embodiment, the check valve 400 is provided at a location where the center line of the bypass pipe 300 faces horizontally, so that the pipe is closed when the valve element 403 hangs down vertically, but the check valve 400 may also be provided at another location on the bypass pipe 300 using a spring or the like that biases the valve element 403 in a closing direction.

[0056] Although an example has been shown in which two drive air intake pipes 200 are provided, namely, the first drive air intake pipe 201 and the second drive air intake pipe 202, more drive air intake pipes may be provided. The materials for the various pipes may be selected appropriately, such as from metal or synthetic resin.

[0057] In this embodiment, the four-way selector valve 24 is provided. The four-way selector valve 24 can be switched between a suction state, which connects the suction port 25a of the water ring vacuum pump 25 to the receiver tank 5 and connects the discharge port 25b of the water ring vacuum pump 25 to an intake / exhaust port of the silencer 23 that exhausts the air discharged from the discharge port 25b, and a pressure state, which connects the discharge port 25b of the water ring vacuum pump 25 to the receiver tank 5 and connects the suction port 25a of the water ring vacuum pump 25 to an intake / exhaust port of the silencer 23 that introduces the air drawn into the suction port 25a. However, the present invention is not limited to this configuration. A four-way selector valve is not required as long as the piping and selector valve are switchable between the suction state and the pressure state. For example, a butterfly valve can be used as the selector valve.

[0058] In addition, in this embodiment, a water ring vacuum pump 25 is used as the vacuum pump of the suction vehicle 1, but the present invention is not limited to this, and a Roots vacuum pump may also be used as the vacuum pump. [Industrial Applicability]

[0059] The present invention can be applied to a suction vehicle that includes a receiver tank for collecting objects to be collected and a vacuum pump for pressurizing or depressurizing the receiver tank. [Explanation of symbols]

[0060] 1 suction car 5 Receiver Tank 15 Operation panel 7a,7b,7c,7d,20,21,24 Suction pipe 23 Silencer (silencer) 24 Air-operated four-way valve (four-way switching valve) 25 Water ring vacuum pump (vacuum pump) 25a Water ring vacuum pump suction port 25b Water ring vacuum pump outlet 100 Ejector 101 Drive air connection port 102 Discharge port 103 Suction air connection port 200 Drive air intake line 201 First drive air intake line 202 Second drive air intake line 203 Merging pipeline 204 Manual valve 300 Bypass Pipe 400 Check valve 402 Hinge 403 Valve body

Claims

1. A suction vehicle equipped with a receiver tank for collecting objects to be collected and a vacuum pump for pressurizing and depressurizing the receiver tank, a suction line capable of communicating with the receiver tank; a drive air intake pipe provided so as to be able to take in air at atmospheric pressure or a pressure higher than atmospheric pressure; an ejector in which the suction pipe line is connected to a suction air connection port, the drive air intake pipe line is connected to a drive air connection port, and the suction port of the vacuum pump is connected to a discharge port; a bypass pipe that communicates the upstream side of the suction pipe from the ejector with a suction port of the vacuum pump; a check valve provided in the bypass pipe line to allow air to flow from the receiver tank side to the suction port side of the vacuum pump while preventing air from flowing back from the suction port side of the vacuum pump to the receiver tank side; Equipped with a silencer is installed at an intake / exhaust port that exhausts air when the receiver tank is depressurized by the operation of the vacuum pump, to silence exhaust noise; the drive air intake pipe includes a first drive air intake pipe, a second drive air intake pipe, and a confluence pipe where the downstream side of the first drive air intake pipe and the downstream side of the second drive air intake pipe join together and are connected to a drive air connection port of the ejector, A suction vehicle characterized in that the upstream side of the first drive air intake pipe is arranged so as to be able to suck in moisture produced in the silencer together with atmospheric air.

2. A suction vehicle equipped with a receiver tank for collecting objects to be collected and a vacuum pump for pressurizing and depressurizing the receiver tank, a suction line capable of communicating with the receiver tank; a drive air intake pipe provided so as to be able to take in air at atmospheric pressure or a pressure higher than atmospheric pressure; an ejector in which the suction pipe line is connected to a suction air connection port, the drive air intake pipe line is connected to a drive air connection port, and the suction port of the vacuum pump is connected to a discharge port; a bypass pipe that communicates the upstream side of the suction pipe from the ejector with a suction port of the vacuum pump; a check valve provided in the bypass pipe line to allow air to flow from the receiver tank side to the suction port side of the vacuum pump while preventing air from flowing back from the suction port side of the vacuum pump to the receiver tank side; Equipped with the bypass pipeline is formed in a substantially S-shape and includes a first bypass pipe extending vertically downward from the upstream side and then turning horizontally, a second bypass pipe extending vertically upward from the downstream side and then turning horizontally, and a horizontal portion between the downstream end of the first bypass pipe and the upstream end of the second bypass pipe; The check valve is a swing-type check valve having a hinge and a valve body attached so as to be swingable via the hinge, and is attached to the horizontal portion.

3. In the suction vehicle described in claim 2, The suction vehicle is characterized in that the ejector is connected to the second bypass pipe so that the discharge port faces a suction port provided on an upper surface of the vacuum pump.

4. The suction vehicle according to any one of claims 1 to 3, a four-way selector valve that can be switched between a suction switching state in which the suction port of the vacuum pump communicates with the receiver tank and the discharge port of the vacuum pump communicates with an exhaust port for discharging air discharged from the discharge port, and a pressurizing switching state in which the discharge port of the vacuum pump communicates with the receiver tank and the suction port of the vacuum pump communicates with an intake port for introducing air sucked into the suction port, The suction vehicle is characterized in that the ejector and the bypass pipe are provided between the four-way switching valve and the suction port of the vacuum pump.

5. The suction vehicle according to claim 2 or 3, the drive air intake pipe includes a first drive air intake pipe, a second drive air intake pipe, and a confluence pipe where the downstream side of the first drive air intake pipe and the downstream side of the second drive air intake pipe join together and are connected to a drive air connection port of the ejector, a manual valve whose opening degree is adjustable is provided on the upstream side of the second drive air intake pipe; The suction vehicle is characterized in that the manual valve is provided adjacent to an operation panel that is operated when pressurizing or depressurizing the receiver tank.

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