Mobile equipment based on a permanently pressurized tank, used for projecting abrasive particles for stripping all types of surfaces
The mobile sandblasting equipment addresses the issue of condensation and abrasive flow disruption by maintaining permanent pressure in the tank using a compact monobloc device, ensuring consistent operation even with low-capacity tanks and fine abrasive powders.
Patent Information
- Application Number
- FR2023012535
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-11-15
- Publication Date
- 2025-05-16
AI Technical Summary
Existing mobile sandblasting equipment experiences condensation of water vapor in the tank due to frequent activation and deactivation of the control handle, leading to amalgamation with abrasive particles and disrupting the flow, especially with fine abrasive powders.
The equipment employs a compact monobloc device with a normally open 3/2 pneumatic control distributor to maintain permanent pressure in the tank, preventing condensation and ensuring consistent abrasive flow, even with low-capacity tanks.
This solution maintains consistent abrasive flow and prevents condensation, reducing the impact of frequent handle deactivations and allowing operation with fine abrasive powders, while also enabling permanent pressure operation of low-capacity tanks.
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
Title of the invention: Mobile equipment based on a permanently pressurized tank in operation, used for projecting abrasive particles for stripping all types of surfaces. Technical field
[0001] Mobile free-jet sandblasters, mobile free-jet surface treatment equipment used for sandblasting, air blasting or hydroblasting of all types of substrates using compressed air to project particles.
[0002] Prior art
[0003] A mobile free-jet sandblaster or surface treatment equipment as mentioned in the "technical field" paragraph is generally based on a tank of variable capacity designed to be pressurized by connecting it to an air compressor.
[0004] Reservoir (1) pressurized and depressurized each time the control handle is activated or deactivated. Schematic diagrams: [Fig. 1] [Fig. 2]
[0005] The tank is connected to an air compressor to supply it with compressed air via the fitting (10). This tank can be equipped with various accessories such as an air separator on the air inlet (12), an air pressure regulator (13), and it is always equipped with a remote control system (14) allowing the spraying to be started and stopped by means of a control handle operated by the operator in accordance with regulations. This tank is generally equipped with a pneumatic closure system based on a rubber cone (4) that presses against a seal (3) installed in a flange (2) when the tubing (5) is supplied with air. When the operator wants to begin the stripping work, wearing their PPE, they operate the control handle which controls the remote control device (14) by means of hoses that connect the handle to this device.Its opening allows the passage of compressed air, the pressure of which can be adjusted by a pressure regulator (13) according to the equipment configuration. Compressed air enters the tank through the tube (5) and simultaneously supplies the mixing point (8) via the tube (9). The abrasive contained in the tank flows through the metering device (11) to mix with the compressed air at the mixing point (8). This compressed air / abrasive mixture is then conveyed to the projection nozzle through the working hose connected to the outlet (15). When the operator wants to stop the projection, they deactivate the control handle, which causes the control device (14) to close. The upper part of the control device (14) is connected to a fitting (16). upper part of the tank. When the handle is deactivated, the control device, which has a valve in its upper part, opens this valve and the compressed air escapes through the silencer (17). The tank is completely depressurized and the rubber cone (4) falls back down. Each time the control handle is activated, the tank is pressurized, and each time the control handle is deactivated, the tank is depressurized. The air, compressed by the compressor, is heated by the pressurization, and the humidity of the ambient air drawn in by the compressor is in the form of water vapor. When the tank is depressurized, the expansion of the air causes significant cooling, resulting in the condensation of water vapor into droplets, due to the dew point. These droplets mix with the abrasive in the tank, creating clumps that are detrimental to the proper flow of the abrasive into the metering unit.The more frequently the handle is deactivated, the greater the problem of water vapor condensation in the tank. This is a major issue, exacerbated by the use of very fine abrasive powders such as those used in sandblasting or wet blasting equipment.
[0006] Reservoir under permanent pressure independent of the activation or deactivation of the control handle. Schematic diagrams: [Fig.3][Fig.4]
[0007] The tank (1) is connected to an air compressor to supply it with compressed air via the fitting (10). This tank can be equipped with various accessories such as an air separator on the air inlet (12) and an air pressure regulator (13). This tank is generally equipped with a pneumatic closure system based on a rubber cone (4) that presses against a seal (3) installed in a flange (2) when the tubing (5) is supplied with air. A valve (14) allows the tank to be pressurized when it is open. Compressed air can then enter the tank but cannot pass through the pilot valve (18), which is closed at rest. The abrasive cannot pass through the metering device (11) because it is also closed at rest.When the operator, wearing their PPE, wants to begin blasting, they activate the control handle, which simultaneously operates the pilot valve (18) and the pilot metering unit (11). These two components open simultaneously, allowing compressed air to pass through the pilot valve (18) and the abrasive through the pilot metering unit (11). The compressed air / abrasive mixture is then routed to the blasting nozzle through the working hose connected to the fitting (15). When the operator wants to stop blasting, they deactivate the control handle, which causes the pilot valve (18) and the pilot metering unit (11) to close simultaneously. Each time the control handle is activated, the pilot valve (18) and the pilot metering unit (11) open simultaneously, allowing compressed air to pass through the valve and the abrasive through the metering unit. The compressed air / abrasive mixture... The air is then routed to the spray nozzle via the working hose. Each time the control handle is deactivated, the pilot valve and the pilot metering unit close, stopping the spray of the compressed air / abrasive mixture at the nozzle. Since the tank remains under constant pressure, the air inside is not replenished, and the humidity remains as water vapor and does not condense. Depressurization is performed manually by opening the valve (19), allowing the compressed air in the tank to escape through the silencer (17). This depressurization is only carried out when the tank is empty and needs to be refilled. The frequency with which the handle is deactivated has no impact on the proper functioning of the equipment. The major drawback of this type of equipment lies in the need for a constant pressure corresponding to the maximum pressure delivered by the compressor at the pilot metering unit.If the compressor flow rate is insufficient relative to the nozzle's consumption, the pressure required to control the metering unit drops, leading to metering unit malfunction, premature wear of certain components, and significant irregularities in abrasive flow. The considerable size of these metering units prevents their installation on small-capacity tanks, making them impossible to mount on some tanks, which consequently cannot be maintained at a constant pressure. Finally, the minimum pressure required to raise the rubber cone and press it against the seal prevents the working pressure from being adjusted below this minimum.
[0008] Description of the invention: [Fig.5][Fig.6][Fig.7][Fig.8][Fig.9]
[0009] Mobile equipment fitted with a variable-capacity tank from 9 to 200 liters, designed to be pressurized with compressed air and to maintain this pressure during operation without being depressurized to stop the spray at the nozzle. The equipment is designed to receive abrasives, stripping powders, or granules used to strip various types of substrates. An innovative on / off device, which allows the compressed air / abrasive mixture to flow to the spray nozzle through a hose while maintaining the tank containing the abrasive under constant pressure, is installed on the equipment. By design, this device can be installed on equipment with very small tank capacities, starting from 9 liters. These tanks can have variable capacities, up to 200 liters, and the air pressure used to pressurize them can be adjustable.
[0010] The reservoir (1) is provided with a flange (2) in its upper part and in its center, in which an O-ring (3) is integrated. A port (6) on the body of this reservoir supplies an internal tube (5) in which a conical rubber sealing system (4) is vertically housed. The compressed air from the com The pressurizer supplies the equipment at the fitting (10), then passes through a settling filter (12), then feeds a ball valve (14) used to pressurize the tank, and then through a pressure regulator (13) connected to a T-fitting (21) which supplies the branch connection (6). A normally open 3 / 2 pneumatically operated valve (18) is interposed between the compressed air supply (10) and the ball valve (14). This valve allows direct control of an on / off device (20) attached to the equipment, installed downstream of the collection point (8) between the compressed air and the abrasive at the outlet of the metering unit (11). The bottom of the T-fitting (21) is connected to an isolation valve (22), which is then connected to the collection point (8) between the compressed air and the abrasive at the outlet of the metering unit (11). A compact one-piece on / off device (20) is connected directly to the outlet of the T at the point of collection of the abrasive or powder contained in the reservoir.This device (20) is traversed by a section of flexible hose (23) fitted with a fitting (24) at its end, allowing the working hose to be connected to it. A ball valve (19) is connected to a branch (16), which is itself connected to a silencer (17). This valve allows manual depressurization of the tank. A pressure regulator (13) is installed to allow adjustment of the air pressure entering the tank and also supplying the collection point (8).
[0011] The working hose connects to the section of hose passing through the device (24). A red and blue twin remote control hose is connected to a control handle located near the spray nozzle at the end of the working hose (not shown). The red hose is connected to the equipment at the elbow (29), and the blue hose is connected to the pilot of the distributor (25). The nipple (26) on the compact on / off monobloc device (20) is connected to the nipple located at the outlet of the distributor (27) by a connecting hose.
[0012] Operating principle:
[0013] At rest, the pressure valve of the tank (14) is closed while the depressurization valve (19) is open. With the supply hose connected to the air inlet of the tank (10) and the air compressor started, the operator, wearing their PPE, closes the depressurization valve (19) and opens the pressure valve (14). The pressure can be adjusted as needed using the pressure regulator (13). The rubber cone (4) is propelled against the O-ring (3) and the tank is pressurized. As soon as compressed air is supplied to the machine, the air reaches the distributor (18) and the on / off device (20) is automatically activated. The section of hose (23) passing through it is pinched, thus preventing any passage of the compressed air / abrasive mixture.
[0014] The operator who wishes to start work operates the control handle, which actuates the distributor (18) which closes and decompresses the hose connected to the nipple (26) of the on / off device (20). The piston (28) in the device is then no longer supplied with compressed air and rises to open the passage for the compressed air / abrasive mixture. This mixture passes through the section of hose (23) integrated into the device (20) and travels along the working hose to the nozzle, where it is then projected onto the surface to be stripped.
[0015] The operator who wishes to stop his work releases the control handle, which deactivates the piloting of the distributor (20), causing the compressed air passage to open at the distributor outlet (27), which allows the on / off device (20) to be repressurized, pinching the piece of hose thus stopping the passage of the compressed air / abrasive mixture.
[0016] Since the reservoir (1) remains under constant pressure, the air it contains is not renewed, and the humidity in the air remains in the form of water vapor and does not condense. The frequency with which the handle is deactivated has no impact on the proper functioning of the equipment. Contrary to the operating principle described in the paragraph illustrated by Figures 3 and 4, the invention is insensitive to a drop in pressure in the event of a compressor with an insufficient flow rate relative to the nozzle consumption and has no impact on the regularity of the abrasive flow through the metering device. The simplicity of the metering device, which can be mounted on the equipment, while allowing operation under constant reservoir pressure thanks to the on / off device (20), as well as its very small size compared to the pilot-operated metering device, are also major advantages.They allow for the operation under constant pressure of small-capacity tanks which would otherwise be impossible due to the impossibility of adapting a pilot-operated dosing system that is too bulky.
[0017] The technical solution for stopping the projection of the compressed air / abrasive mixture offered by the compact monobloc on / off device (20) in relation to equipment with a permanently pressurized tank constitutes an important innovation with many applications, in particular to allow the operation of small capacity tanks under permanent pressure.
[0018] Existing technical solutions for stopping the projection of the compressed air / abrasive mixture from equipment whose tank is under permanent pressure are illustrated in Figures (3 and 4) and have been described previously. They are all based, on the one hand, on stopping the flow of compressed air to the collection point (8) by a pneumatically or electrically controlled valve upstream of this collection point (8), and on the other hand, on stopping the flow of the abrasive through a metering device also pneumatically or electrically controlled, which implies controlling these two elements separately and simultaneously to stop the projection of the compressed air / abrasive mixture at the nozzle.
Claims
Claims
1. : [Fig 5] [Fig 6] [Fig 7] [Fig 8] [Fig 9] Mobile free jet stripping equipment on wheels, based on a tank (1) with a capacity of at least 9 liters and up to a maximum of 200 liters, provided with a flange (2) in its upper part and in its center in which an O-ring (3) is integrated. A tapping (6) on the body of this tank makes it possible to feed an internal tube (5) in which a conical rubber sealing system (4) is housed vertically. Compressed air from the compressor feeds the equipment at connection (10) then passes through a decanter filter (12), then feeds a ball valve (14) used to pressurize the tank, then passes through a pressure regulator (13) connected to a T (21) which feeds the tapping (6) as well as the collection point (8) passing through an isolation valve (22) and the tubing (9).A normally open 3 / 2 pneumatically controlled distributor (18) is interposed between the compressed air supply (10) and the ball valve (14). This distributor (18) allows direct control of an on / off device integral with the equipment (20), installed downstream of the collection T (8) between the compressed air coming from the outlet of the T (21) and the abrasive flowing through the metering device (11). The bottom of the T (21) is connected to an isolation valve (22), then this valve is connected to the T (8) constituting the collection point between the compressed air and the abrasive flowing through the metering device (11). A ball valve (19) is connected to a connection (16), itself connected to a silencer (17). This valve allows manual depressurization of the tank. The working hose connects to the fitting (24) at the end of the piece of hose (23) passing through the on / off device (20).Red and blue remote control hoses (not shown) are connected to a control handle (not shown) located near the spray nozzle at the end of the working hose. The red hose is connected to the elbow with the nipple (29) and the blue hose is connected to the distributor pilot (25). The equipment is characterized by the on / off device (20) connected directly to the outlet of the T (8) at the collection point of the abrasive contained in the tank, T where the compressed air coming from the outlet of the T (21) and the abrasive flowing through the doser (11) mixes. This device is crossed by a piece of hose (23) provided with a connector (24) at its end allowing the connection of the flexible working hose. As soon as compressed air is admitted to the equipment inlet (10), the on / off device (20) is automatically supplied with compressed air via a hose (not shown) connected between the connection (27) of the 3 / 2 normally open distributor (18) and the connection (26) on the device (20). The piston of the device (28) is actuated, which compresses the piece of hose (23). When the operator wishes to start his work, he operates the control handle (not shown), the signal is sent to the normally open distributor (18) through the blue hose connecting the handle (not shown) to the nipple (25). The distributor (18) closes the passage of compressed air, which is no longer conveyed to the device (20) via a hose connected between the nipple (27) at the distributor outlet (18) and the nipple (26) on the inlet of the on / off device (20). The piston (28) is no longer actuated and frees the passage in the piece of hose (23). At rest, when the equipment is not in use, the tank pressurization valve (14) is closed, while the depressurization valve (19) is open. With the supply hose connected to the tank air inlet (10) and the air compressor started, the operator wearing PPE closes the depressurization valve (19) and opens the pressurization valve (14). The pressure can be adjusted as required using the pressure regulator (13). The rubber cone (4) is propelled against the O-ring (3) and the tank is pressurized. As soon as the compressed air feeds the machine, the compressed air feeds the distributor (18) and the on / off device (20) is automatically activated by the passage of the compressed air through the distributor to the nipple (27) connected by a hose to the nipple (26) of the on / off device (20).The piece of hose (23) that runs through it is pinched, thus preventing any passage of air / abrasive mixture. The operator who wishes to start his work operates the control handle, which supplies the distributor (18) via the blue hose (not shown) connected between the handle and the nipple (25). The distributor (18) closes the passage of compressed air to the nipple (27). The hose connected between this nipple and the nipple (26) of the on / off device (20) is decompressed and no longer supplies the device. The piston in the device (28) is then no longer supplied with compressed air and rises to free the passage of the compressed air / abrasive mixture through the piece of hose (23) that runs through the on / off device (20). This mixture passes through the piece of hose (23) and travels through the. flexible working hose (not shown) to the nozzle (not shown) to then be projected onto the support to be stripped. The operator who wishes to stop his work releases the control handle, which deactivates the piloting of the distributor (18), the air pressure no longer reaching the nipple (25) connected to the control handle by the blue hose (not shown). The distributor (18) opens the passage of compressed air to the connector (27), the hose connected between this nipple and the nipple (26) of the on / off device (20) is supplied with compressed air. The piston of the device (28) is actuated, which crushes the piece of hose (23), thus stopping the passage of the compressed air / abrasive mixture which is no longer conveyed into the working hose. The manipulations of the control handle by the operator activate or deactivate the piloting (25) of the distributor (18), which causes the on / off device (20) to be pressurized or depressurized.When the on / off device (20) is supplied by the distributor (18), the piece of hose (23) passing through it is pinched, preventing the passage of the compressed air / abrasive mixture. When the on / off device (20) is not supplied by the distributor (18), the piece of hose (23) is no longer pinched, which frees the passage of the compressed air / abrasive mixture. The tank remains under pressure at all times without being disturbed by the operator's manipulations of the control handle to start or stop the projection of the compressed air / abrasive mixture at the nozzle. The tank is only depressurized when the operator decides to depressurize the tank, when it is empty and it needs to be refilled. The operator closes the valve (14), which no longer allows compressed air to pass to the mixing point (8) or to the tapping (6) which feeds the tubing (5). The operator opens the valve (19), which allows the air contained in the tank to be evacuated through the silencer (17) mounted under the valve (19). Once the tank is depressurized, the rubber cone (4) falls, which allows the tank to be filled. Once the tank is filled, the operator closes the valve (19) and opens the valve (14), which causes the tank to be repressurized.During the entire time the equipment is powered by the compressor, the on / off device (20) is continuously supplied with compressed air by the distributor (18) and the piece of hose (23) is pinched, not allowing any passage of the compressed air / abrasive mixture to the working hose. Only the activation of the. remote control handle, connected by the blue hose to the pilot (25) of the distributor (18), allows the air passage to be closed towards the outlet (27), which decompresses the hose connected to the nipple (26) of the on / off device (20). The device no longer being supplied with compressed air, the piston (28) no longer crushes the piece of hose (23), which frees the passage and allows the compressed air / abrasive mixture to be conveyed towards the working hose, as long as the control handle remains activated by the operator.
2. The on-off device (20), the operation of which is described in claim 1, is characterized by its base (30) into which a connector (33) is inserted. The connection of the base to the outlet of the compressed air / abrasive mixture is made by means of the nipple (34). A piece of hose (23) is inserted into the connector (33). It is secured to this connector and to the base (30) by two screws (35). The second screw is not visible in the view, it is located opposite the first, at 180° from it. The screws pass through the base (30) and the connector (33) to screw into the hose (23). The reduced size of the base (140 x 160 mm) allows the device to be mounted on tanks of reduced capacity, from 9 liters.
3. The on / off device (20) is also characterized by the design of its piston (28) incorporating two grooves which allow two identical O-rings to be received. This piston operates in a bell (37) which is secured to the base by two bolts (31). The piston slides on two spacers (32). The actuation of the piston is driven by compressed air coming from the outlet (27) of the normally open 3 / 2 distributor (18) connected to the nipple (26) mounted on an elbow in the upper part of the bell.