AN AUTOMATIC ASPIRATOR-TRANSFER VALVE, AND A JET WASHING APPARATUS COMPRISING SUCH A VALVE

Abstract: In an automatic aspirator-transfer valve controlling the delivery of washing fluid from a supply (M) to a cleaning gun (B) and having a valving piston (2) movable between a first or rinsing position, in which it opens bypass con­ duits (15) bypassing an injector (3,21,4) and a second or washing position in which it closes said bypass conduit (15) and enables the injector (3,21,4) to aspi­ rate washing fluid from a reservoir (not shown) through a non-return valve (11), a side inlet (5) and a conduit (22) to its side inlet (21), the novel aspect is that the side inlet conduit (22) is separated from the space within the housing bore (20), in which the valving piston (2) can slide. In this manner it is avoided that a portion of the washing agent may fill the space within the housing bore (20) and leave the valve in the form of a "plug" when changing from the washing mode (Bottom Figure) to the rinsing mode , thus avoiding both the issuing of dangerously high concentrations and unnecessary waste of washing agent.

Description: The present invention relates to an automatic aspirator-transfer valve of the kind comprising a) a housing with a first inlet, a second inlet and an outlet, b) an injector placed between and communicating with said first inlet and said outlet, and having a side inlet c) a housing bore between and communicating with said first inlet and said injector, and d) a valving piston with a passage interconnecting its both ends, the upstream end communicating with said housing inlet and the downstream end communicating with the inlet nozzle of said injector, said piston being slidable under the influence of variations in pressure differentials between surfaces facing upstream and surfaces facing downstream between a first, upstream-most position (Figures 1, 4 and 6), in which the downstream end of said piston passage communicates through an open valving gap between the downstream end of the piston and an upstream extension of said injector inlet nozzle with bypass conduits leading to said housing outlet, and a second, downstream-most position (Figures 3, 5 and 7), in which said valving gap is closed by the downstream end of said piston engaging said upstream extension. Such a valve is disclosed in U.S. Patent Specification No. 3,613,997 (Richard G. Thompson), vide especially the Specification's Figure 3. In this known aspirator-transfer valve, the inlet path through the side inlet 25a of the injector 23a, 25a, 24a passes through the space inside the housing bore 16a, so that when the valve is in the mode (not shown) for adding washing agent from a housing side inlet 14a, i.e. when the valving piston 18a separates the upstream end of the bypass conduits 28a from the space inside the housing bore 16a to the outlet 15a, the entire said space inside the housing bore 16a will be filled with concentrated washing agent, only a non-return valve 26a, 27a preventing the washing agent from spreading further into said bypass conduits, or from being diluted by fluid from same, depending on relative pressures. When changing from said washing-agent mode to the rinsing mode, in which the piston 18a is withdrawn upstream and allows washing fluid to pass directly from the housing inlet 13a to the housing outlet 15a through said bypass conduits 28a, the volume of washing agent present in said space inside the housing bore 16a will be flushed out through the outlet, causing a "plug" of concentrated washing agent to travel along the outlet hose 51 (vide Figures 1 and 2 of the same Specification) to the cleaning gun 53. One disadvantage of this is that the ensuing concentration of washing agent applied to the object being treated may be higher than the material of said object will tolerate, so that irreparable damage may result. Another disadvantage is that the washing agent in its undiluted form may be dangerous for the operator, and a third disadvantage is the obvious waste of washing agent involved, as the transition from the washing mode to the rinsing mode represents a situation, in which the operator does not intend to use any more washing agent, but only the washing fluid, such as for rinsing after washing or scrubbing the object concerned. It is admittedly known from EP-A-144 047 to provide a valve in which the connection between a side inlet of an injector and a second housing inlet is constructed by a conduit separate from a bypass conduit. However, in this known embodiment a special valve must be actuated by hand to change over from the flow of water alone to the flow of water plus additive. It is the object of the present invention to provide an automatic aspirator-transfer valve of the kind referred to above, in which the disadvantages described above are eliminated or at least substantially reduced. The above-mentioned object of the invention is attained in a valve of the kind referred to initially, which according to the invention is characterized in e) a chamber between the inlet nozzle (3) and the outlet nozzle (4), which chamber communicates with the side inlet (21) of the injector (3,4) and communicates also with the second inlet (5) on the outside of the housing (1) through at least one conduit (22) separated from said bypass conduits (15). With such a valve, the washing agent is conducted to the side inlet of the injector through a path completely separated from the space inside the housing bore, so that the issuing and waste of concentrated washing agent described above is avoided. Furthermore, the non-return valve between said space and the bypass conduits is no longer necessary, and may be dispensed with, thus simplifying the construction of the valve. The present invention also relates to a washing apparatus for alternately effecting washing at low pressure and high-pressure jet cleaning and of the kind comprising a) a supply of washing fluid at high pressure, b) a supply of washing agent to be admixed to said washing fluid during periods of washing at low pressure, c) an automatic aspirator-transfer valve of the kind initially referred to, and d) a gun comprising at least one outlet nozzle for fluid supplied through said valve from said supply or supplies, said gun having means for increasing the flow cross-sectional area in order to lower the pressure in the outlet from said valve for controlling its operation. According to the present invention, this apparatus is characterized in e) that said valve is a valve exhibiting the features of the present invention mentioned in paragraph e) above, possibly also further features according to the invention to be described below, and f) that said gun comprises more than one nozzle and is arranged alternately and under manual control to connect a smaller number of nozzles or a greater number of nozzles to the outlet of said valve, so as to effect the requisite change in flow cross-sectional area for controlling said valve. The present invention is now to be explained in a more detailed manner with reference to the diagrammatic drawing, in which Figure 1 shows a first exemplary embodiment of an automatic aspirator-transfer valve according to the present invention, shown in longitudinal section in the mode corresponding to high-pressure rinsing without washing agent. Figure 2 in the same manner as Figure 1 shows the same valve in an intermediate position between two modes of operation, Figure 3 in the same manner as Figures 1 and 2 shows the same valve in an end position in a mode corresponding to low-pressure washing with a washing agent added to the washing fluid, Figures 4 and 5 in the same manner as Figures 1-3 show a second exemplary embodiment of a valve according to the present invention, in the high-pressure rinsing mode and the low-pressure washing mode respectively, and Figures 6 and 7 in the same manner as above show a third exemplary embodiment of a valve according to the invention, in the high-pressure rinsing mode and the low-pressure washing mode respectively. In the embodiment shown in Figures 1-3, an automatic aspirator-transfer valve comprises a housing 1 with an inlet 18 connected to a supply M (shown purely in symbolic form) arranged to deliver washing fluid, such as water, at a pressure of the order of at least 5-10 bars (1 bar = 10⁵ Pa). The valve's outlet 19 is connected through a hose 12 to a cleaning gun B with two nozzles C, so arranged that one or two nozzles C or none of them may be connected to the hose 12 by manually operating suitable means on the gun B. Directly communicating with said inlet 18 is a housing bore 20, in which a valving piston 2 is slidably supported in such a manner as to be movable from the upstream-most position shown in Figure 1 to the downstream-most position shown in Figure 3, Figure 2 showing an intermediate transition position. The piston 2 has a passage 17 extending from its upstream end to its downstream end, thus connecting the housing inlet 18 to the downstream (right-hand) end of the bore 20 and to an inlet in the form of an upstream extension 16 on an injector inlet nozzle 3, said injector having a side inlet 21 and an outlet nozzle 4. The outlet nozzle 4 communicates with the housing outlet 19 referred to above. The downstream end of the bore 20 also communicates with the housing outlet 19 through at least one bypass conduit 15 bypassing the injector 3, 21, 4. The side inlet 21 of this injector communicates with the exterior of the housing 1 through an injector inlet conduit 22 and a housing side inlet 5, the latter communicating with a washing agent reservoir (not shown) through a non-return valve 11. In the embodiment shown in Figures 1-3, as well as in the embodiment shown in Figures 4 and 5 to be described below, both the housing bore 20 and the valving piston 2 are stepped to form portions with two different effective diameters d₁ and d₂, the resultant difference in cross-sectional area being in such a direction, that the pressure difference arising when the same pressure is applied to both ends tends to move the piston 2 in the upstream direction, i.e. towards the left in the drawing. Seals 9 and 10, a vent 8 and a hole 25 ensure the proper operation of the piston 2 in this respect, preventing both leakage and the formation of pressure pockets. In the embodiment shown, a helical compression spring 6 is inserted on the piston 2 between an annular abutment surface 26 and a ring abutment 24, the latter having a sufficiently small diameter to permit the upstream part 27 of the piston 2 to enter into a recess 28 formed at the upstream end of the housing bore 20, so that the spring 6 may be compressed on the upstream part 27 by a spring abutment ring 23 slidable on said upstream part, but not past the ring abutment 24, vide Figures 1 and 2. When the washing apparatus, of which the aspirator-transfer valve shown is a part, is put into operation, fluid pressure is first applied through the housing inlet 18, and then this fluid pressure is propagated through the piston passage 17 and from there through two paths, the first of which goes through the injector 3, 21, 4 to the outlet 19, and the second through the bypass conduit(s) 15, likewise to the outlet 19. If at this stage only one of the two outlet nozzles C is open, the flow resistance downstream of the outlet 19 will be sufficient to maintain a considerable pressure in the housing bore 20, so that the pressure difference arising through the diameter difference referred to above will move the valving piston 2 upstream against the force of the spring 6 as shown in Figure 1, thus creating an annular gap 7 of considerable flow cross-sectional area between the inside of the downstream end of the piston passage 17 and the outside of the upstream extension 16 on the inlet end of the injector 3, 21, 4. As the injector 3, 21, 4 is now substantially "short-circuited" by the bypass conduit(s) 15, the pressure difference between its ends is insufficient to cause a flow through the injector of sufficient velocity to cause the aspiration of washing agent against the threshold pressure of the non-return valve 11, this valve preferably being of the ball-and-spring type. The injector 3, 21, 4 thus being inactive, only pure washing fluid, such as water, is transferred from the supply M under high pressure to the one outlet nozzle C being open, and will issue therefrom as a high-velocity jet suitable for rinsing purposes. If now also the other one of the outlet nozzles C is opened, then the flow resistance of the conduits (not shown) upstream of the housing inlet 18 will be sufficient to cause a drop in pressure within the housing bore 20, so that the force of the spring 6 will be sufficient to overcome the pressure difference acting on the valving piston 2 and to move the piston through a distance in the downstream direction to the intermediate position shown in Figure 2. In this position, the flow cross-sectional area of the annular gap 7 is reduced, causing a further drop in pressure in the downstream end of the housing bore 20, but not in the upstream end, the restricted gap lying in-between. The pressure difference acting on the valving piston 2 will now be in the opposite direction, i.e. acting in the downstream direction, and the piston 2 will move further, unaided by the spring 6, to the end position shown in Figure 3, in which the annular gap 7 is completely closed by its valving surfaces 13 and 14 on the injector inlet nozzle 3 and the piston 2 respectively engaging each other, thus constraining all flow through the injector 3, 21, 4. The fluid now leaving the outlet 19, and hence issuing from both of the two outlet nozzles C, will now consist of washing fluid, such as water, with a washing agent, such as a detergent or surfactant, added thereto by being aspirated by the injector 3, 21, 4 through the inlet conduit 22, the side inlet 5 and the non-return valve 11 from a washing agent reservoir (not shown). As the pressure at the entrance to the outlet nozzles C is now comparatively low, the mixture of washing fluid and washing agent will issue at a comparatively low velocity, suitable for washing and/or scrubbing purposes. In the embodiment shown in Figures 1-3, the upstream extension 16 on the injector 3, 21, 4 is comparatively short, thus leaving a fairly large flow cross-sectional area in the annular gap 7 in the high-pressure rinsing position shown in Figure 1, so that the pressure drop across this gap is small. This is advantageous when using a low-pressure supply M delivering fluid in the pressure range mentioned above, i.e. between 5 and 10 bars or more, as a high pressure drop at this location could otherwise compromise the effect of the pressure difference caused by the difference in the two effective diameters d₁ and d₂. At higher supply pressures in the range around 160 bars or more, such as delivered by the supply S shown in Figures 4 and 5, it may, however, be expedient to have a smaller flow cross-sectional area in the gap 7 in this position, as this ensures a permanent, but small pressure difference facilitating the transition from an intermediate position (not shown) corresponding to the one shown in Figure 2 to the end position shown in Figure 5. The reduced flow cross-sectional area in the annular gap 7' shown in Figures 4 and 5 is attained by using an upstream extension 16' of increased axial length. The size of the annular gap 7 or 7' may also be varied by altering the inside diameter of the downstream end of the piston passage 17 and/or the outside diameter of the upstream extension 16 or 16' - or part of same. In the embodiment shown in Figures 6 and 7, the difference between the effective diameters d₁ and d₂ on the two portions of the piston 2 has been increased by placing the housing inlet 18' laterally to the housing bore 20' and letting a reduced-diameter extension 28 of the piston 2 extend through an opening 29 in the end wall of the housing 1, said opening 29 and reduced-diameter extension 28 being sealed against each other by a seal 30. Holes 31 allow the fluid to pass from the inlet 18' to the piston passage 17'. The embodiment shown in Figures 6 and 7 is especially suitable for use with a supply M delivering fluid at a comparatively low pressure, such as from 15 to 20 bars or more, and provides the additional advantage that the protruding end of the piston extension 28 may be used to indicate visually the position of the piston 2, i.e. whether the gap 7 is open or closed. As can be seen from Figures 1, 4 and 6, the quantity of washing agent in direct communication with the side inlet 21 of the injector 3, 21, 4 is limited by the volume of the side inlet conduit 22 and the volume of the side inlet 21 itself. As the non-return valve 11 prevents flow of washing agent into these spaces, and the injector 3, 21, 4 is "short-circuited" by the bypass conduit(s) 15, the amount of washing agent being carried into the stream of rinsing fluid will be extremely small, if at all perceptible. This effect is enhanced by the fact that the bypass conduit(s) 15 extend(s) in continuation of the annular gap 7 or 7', said gap diverging in the downstream direction, so that the combined flow path consisting of the gap 7 and the bypass conduit(s) 15 will offer a relatively small resistance to the stream of rinsing fluid. Numerous modifications to the embodiments described above and shown on the drawings are possible within the scope of the present invention as defined in the claims. Thus, the entrance end of the injector's inlet nozzle 3 and the exit end of the injector's outlet nozzle 4 could be fitted with spring-loaded valves, such as non-return valves, in order to prevent completely any washing agent from flowing into the system when the equipment is in the rinsing mode. Such valves would, of course, have to be dimensioned to open at sufficiently low threshold pressures to ensure proper functioning of the injector 3, 21, 4. The materials used for the various components of the aspirator-transfer valve according to the present invention may be such as persons skilled in this art would select in a known manner, such as brass or stainless steel for the rigid parts, synthetic rubber for the seals, and spring steel for the spring 6 and for any valve springs (not shown), such as in the non-return valve 11 and the spring-loaded valves referred to in the preceding paragraph. It should be noted that the delivery pressures for the supplies M and S referred to above are the so-called "circulatory pressures" of the units concerned. The "circulatory pressure" of units of the kind referred to herein is the pressure measured in the outlet of the unit when the outlet is blocked, and the fluid circulates within the unit whilst the pump is still running. The effective delivery pressure when fluid is being delivered may - due to the nature of the automatic control equipment used in such units - both be higher and lower than said "circulatory pressure", preferably higher. A "circulatory pressure" that is lower than the delivery pressure will, of course, entail a saving in energy when the unit is working against a closed system, as the power lost in pumping fluid against a pressure drop will be less.

Claims: An automatic aspirator-transfer valve of the kind comprising a) a housing (1) with a first inlet (18), a second inlet (5) and an outlet (19), b) an injector (3,4) placed between and communicating with said first inlet (18) and said outlet (19), and having a side inlet (21), c) a housing bore (20) between and communicating with said first inlet (18) and said injector (3,4), and d) a valving piston (2) with a passage (17) interconnecting its both ends, the upstream end communicating with said housing inlet (18) and the downstream end communicating with the inlet nozzle (3) of said injector (3,4), said piston (2) being slidable under the influence of variations in pressure differentials between surfaces facing upstream and surfaces facing downstream between a first, upstream-most position (Figures 1, 4 and 6), in which the downstream end of said piston passage (17) communicates through an open valving gap (7, 7') between the downstream end of the piston (2) and an upstream extension (16,16') of said injector inlet nozzle (3) with bypass conduits (15) leading to said housing outlet (19), and a second, downstream-most position (Figures 3,5 and 7), in which said valving gap (7, 7') is closed by the downstream end of said piston (2) engaging said upstream extension (16,16'), characterized by e) a chamber between the inlet nozzle (3) and the outlet nozzle (4), which chamber communicates with the side inlet (21) of the injector (3,4) and communicates also with the second inlet (5) on the outside of the housing (1) through at least one conduit (22) separated from said bypass conduits (15). A valve as claimed in claim 1, characterized in that the downstream end of said piston (2) and said upstream extension (16,16') of said injector inlet nozzle (3) are mutually shaped in such a manner as to allow one to enter into the other, forming said valving gap (7, 7'). A valve as claimed in claim 2 and with said housing bore (20) and said injector (3,4) with said upstream extension (16,16') substantially coaxial with each other, characterized in a) that said downstream end of said piston (2) and said upstream extension (16,16') of said injector inlet nozzle (3) are mutually shaped in such a manner as to allow said downstream extension (16,16') to enter into the downstream end of said piston passage (17), so that said valving gap (7, 7') formed thereby when open diverges in the downstream direction, and b) that said bypass conduits (15) extend generally in continuation of said valving gap (7, 7') towards said housing outlet (19). A valve as claimed in any or any one of the claims 1-3 and having a spring (6) axially influencing said piston (2), characterized in that said spring (6) is arranged to influence said piston in a direction away from said first, upstream-most position towards said second, downstream-most position. A valve as claimed in claim 4, characterized in that said spring (6) is arranged to influence said piston in said direction only through a first part of its possible stroke of movement from said first position to said second position. A valve as claimed in any or any one of claims 1-5 and having a spring (6) influencing said piston (2), characterized in that said spring (6) is placed on the outside of said piston (2) inside said housing bore (20). A washing apparatus for alternately effecting washing at low pressure and high-pressure jet cleaning and of the kind comprising a) a supply (M,S) of washing fluid at high pressure, b) a supply (at 5) of washing agent to be admixed to said washing fluid during periods of washing at low pressure, c) an automatic aspirator-transfer valve of the kind set forth in the preamble of claim 1, and d) a gun (B,C) comprising at least one outlet nozzle (6) for fluid supplied through said valve from said supply or supplies, said gun having means for increasing the flow cross-sectional area in order to lower the pressure in the outlet from said valve for controlling its operation, characterized in e) that said valve is a valve having also the features set forth in the characterizing clause of claim 1, possibly also the features set forth in any or any one of the claims 2-6, and f) that said gun (B,C) comprises more than one nozzle (C) and is arranged alternately and under manual control to connect a smaller number of nozzles or a greater number of nozzles to the outlet of said valve, so as to effect the requisite change in flow cross-sectional area for controlling said valve. A washing apparatus as claimed in claim 7, characterized in that said smaller number is one. A washing apparatus as claimed in claim 8, characterized in that said greater number is two.

Inventors: OSTERGAARD, TAGE
Applicants: K.E.W. INDUSTRI A/S
Application year: 1986
Main classification: F16K11
IPC codes: F04F5, B05B7, B05B12, B08B3