FR2721172A1 - Pressure regulator for agricultural spreading machine - Google Patents

Abstract

The pressure regulator is for a spreading machine in which liquid from a pump (P) flows through a pipe (5) into a chamber (7). A part of the liquid flows through a filter (11) and after traversing throttle holes (12) ejects (A) to a spreader. The remainder of the liquid flows into a distribution chamber (8). From the distribution chamber (8) a part of the liquid flows on a return path (R,22) back to the reservoir and part on a by-pass route (B) to the reservoir agitator. The liquid flows are regulated at throttle points (15,29) by a motor-driven piston (25,14) and also controlled by a motor-driven three-way outlet valve (26,24).

Description

PRESSURE REGULATOR FOR MOBILE DEVICE
AGRICULTURAL EJECTION
The invention relates to a pressure regulator for a mobile device for agricultural use for ejecting a liquid from a tank, comprising a flow compartment disposed in an envelope of the regulator, compartment of which an ejection pipe goes towards the ejection device, a return line goes to the tank, and a bypass line goes to an agitator arranged in the tank, both the return line and the bypass channel each being provided with a throttling point adjustable.

 Known from the German utility model 93 01 935.1 is a pressure regulator intended for an ejection device for agricultural use. The pressure regulator comprises an envelope in which a distribution chamber is provided. From a top side, a filter cartridge is inserted into this distribution chamber intended to filter the flow of liquid passing through the distribution chamber. On its inlet side, the distribution chamber is connected to a pressure line, which comes from a liquid storage tank. On the outlet side, an ejection compartment leaves the distribution chamber, the stream of liquid sent to the ejection pipe being filtered, in the distribution chamber, passing through the filtration device. The ejection pipe leads to this ejection device, which preferably is provided with spray nozzles or the like. On the outlet side, a return line, the flow rate of which is adjustable using an adjusting device, is connected to the distribution chamber. The return line is, at a return line, connected to the storage tank, the return line can be directed alternately to a main return line or to a line of an agitator, to operate an agitator in tank. In particular for relatively low spray pressures of the ejection device, it is however no longer possible to operate the agitator by means of the derivative return current.

 In the application for a German utility model which has not been the subject of a prior publication G 94 09 680.5, a pressure regulator for a mobile ejection device for agricultural use is described, in the envelope of which provides a filtration device that can be inserted into a drainage compartment. An ejection pipe leaves the flow compartment to reach the spray nozzles of the ejection device. A return line, which opens into a return line going to the tank intended for the liquid to be ejected, leaves & & from an area of the flow compartment having a high dynamic pressure.

Furthermore, a bypass pipe, which opens into an agitator line leading to an agitator arranged in the tank, leaves from the area of the flow compartment at high dynamic pressure. The flow rates prevailing in the return line and in the bypass line can be controlled using throttling devices, each of which can be adjusted continuously using its own adjusting device. In this way, the pressure in the ejection pipe is adjusted simultaneously. Thanks to the presence of the bypass pipe leading to the agitator, the supply of liquid to the agitator is independent of the pressure prevailing in the return pipe, so that, in conjunction with the large dynamic pressure prevailing in a certain area of the flow compartment, even at low spray pressures, it is ensured that the agitator is operated. The flow compartment has an area with high dynamic pressure, as well as an area with low dynamic pressure.

 The invention aims to provide a pressure regulator of the type described above, which has a simple structure, and which nevertheless allows, even at low spray pressures, a significant adjustment of the spray pressure, in connection with an agitator maneuver.

 This object is achieved by the fact that the two throttling points can be controlled simultaneously using a common adjustment device, the throttling point of the bypass pipe being provided with a throttling function located , relative to the throttling point of the return line, upstream in the direction of opening. Therefore, a single adjustment device is sufficient to regulate the flow rate both in the return line and in the bypass line. This results in time-shifted throttle functions, with the aid of which one of the two choke points is late, so that, even for a complete flow passing through one of the two pipes, one may have a further reduction in spray pressure in the discharge line, as required. Because only a common adjustment device is provided, an adjustment device is saved, compared to the pressure regulator described above, which leads to a simpler structure, for the same possibilities of functions.

 In one embodiment of the invention, the device for adjusting each choke point comprises a drawer, these drawers being rigidly connected to one another to allow common linear movement, so that one of the drawers, in the direction of movement, and over a certain length, bears in a sealed manner against the throttling seat which is assigned to it, this length corresponding approximately to the stroke of the other drawer. In another embodiment of the invention, the two drawers are designed as different axial zones of an adjustment piston which can undergo a continuous displacement, which piston, in motion, is arranged horizontally in the envelope of the pressure regulator . Therefore, the adjusting piston has a double function, because it regulates on the one hand the flow through the bypass line, and also the flow through the return line.

 In another embodiment of the invention, there is in the area of the outlet of the return pipe and the outlet of the bypass pipe going to the tank a three-way valve, in active communication with the two outlets , continuously adjustable valve. Therefore, it is possible to continuously subdivide the amount stirred between the agitator and the return line going to the tank. Such a continuous subdivision is particularly advantageous when the stirring effect is too intense.

 The object according to the invention is achieved by the fact that there is provided in a zone of the flow compartment arranged, in the direction of flow, in front of a distribution chamber, a retaining device for increasing the dynamic pressure of the liquid stream, area from which the bypass pipe leads to the agitator. Thanks to the bypass of the bypass pipe in front of the distribution chamber, the supply of liquid to the agitator is independent of the pressure prevailing in the return pipe. Thanks to the retaining device, one arrives, even at low spraying pressures, at a sufficient dynamic pressure in front of the distribution chamber, which guarantees a maneuver of the agitator.

Therefore, it is possible to stir the liquid in the tank even at low spray pressures.

 In another embodiment of the invention, there is provided as a retaining device a shutter disposed in the transition zone between the zone of the flow compartment and the distribution chamber. This is a particularly simple and inexpensive embodiment, but which simultaneously ensures sufficient functionality.

 In another embodiment of the invention, the return pipe and the bypass pipe are guided, in the regulator casing, in planes parallel to each other. Despite the separate path of the return line and the agitator line, we still arrive at a compact envelope.

The invention will be better understood with reference to the description below and the appended drawings, which represent an embodiment of the invention, drawings in which
Figure 1 shows in longitudinal section an embodiment of a pressure regulator according to the invention, in which the ejection channel going to the ejection device is not shown, and where, in the envelope of the pressure regulator, there is a bypass line going to an agitator, as well as a return line going to a storage tank
Figure 2 is a section through the pressure regulator according to Figure 1 along line II-II of Figure 1, and
Figure 3 is a side view of part of the casing of the pressure regulator according to Figure 1 in the direction of arrows III, from which the casing part having the filter cartridge has been removed.

 A pressure regulator according to FIGS. 1 to 3 is provided to regulate the spraying pressure of a spraying boom which can be moved using an agricultural tractor, a boom which ejects a sprayed liquid, such as a fertilizer or pesticide agent. The spray liquid is stored in a storage tank, located on the agricultural tractor. The spraying pressure necessary for the pressure regulator is itself regulated by a pump depending on the running speed of the tractor, a pump which, on the pressure inlet side, is arranged between the pressure regulator and the storage tank. .

To be able to mix the spray liquid in the tank and thus ensure a homogeneous mixture over a long period of time, an agitator is placed in the tank, an agitator which tangentially introduces the spray liquid from the regulator into the tank. pressure, with the production of a mixing operation, which is not necessary for the spraying operation of the spray boom. The pressure regulator comprises an envelope made up of four envelope parts (1 to 4). An envelope part (1) comprises a flow compartment (6), extending over its entire height, flow chamber which, on the inlet side, is provided with a connection tube (5) intended for a pipe pump from the pump.

By inserting a filter cartridge element (10), zones with different dynamic pressures are obtained in the flow compartment (6). The filter cartridge part (10) is inserted from above into the casing part (1), and is essentially formed in accordance with a filter cartridge known from the German utility model G 93 01 935.1.

The filter cartridge part (10) comprises, in a lower zone, a filter (11), and, thanks to its special structure, subdivides the flow compartment (6) into two zones having different dynamic pressures.

Between a distribution chamber (8) which represents a central zone of the flow compartment (6), and a lower zone, adjacent to the connection pipe (5), the filter cartridge has on its outer periphery several throttling holes (12), representing a shutter, holes through which a dynamic pressure greater than that prevailing in the distribution chamber (8) is produced in the lower zone of the flow compartment (6). The core of the filter cartridge part (10) is designed with an axial recess, so that the pump flow (P) supplied to the flow compartment (6) is subdivided into an ejection current (A) sent to an ejection pipe, not shown, which communicates with the spraying boom, and in a partial current with axial passage. The ejection current (A) leaves the distribution chamber (8), and the partial current with axial throttle not throttled flows, in the lower zone (7) of the flow compartment (6), coaxially towards the top, and, in the upper area of the filter cartridge part (10), is radially and laterally discharged to the outside, by means of radial return openings (9) arranged in the filter cartridge (10), to arrive in a bypass line (13) (bypass current B). A return current (R) is, like the ejection current (A) - in the direction of flow - drawn from the distribution chamber (8), downstream of the throttle holes (12). The envelope part (1) is laterally connected with an envelope part (2), in which both the bypass line (13) and the return line (30) for the return current (R) continue. The bypass line (13), like the return line (30), runs in planes parallel to each other. The return line (30) intended for the return current (R) is located, in FIG. 1, and in the direction of sight, in front of the plane of the drawing, and this is the reason why the arrows corresponding to the current return are only shown in dashes.

 The flow rate in the bypass line (13), like the flow rate in the return line (30), is regulated using a common control piston (14), which can be adjusted by 'in a continuous manner using an electric motor (25) disposed in an envelope part (3) and a corresponding pin control. Relative to the vertical filter cartridge (10), the adjustment piston (14) is arranged in a horizontal position in the casing part (2) and can also undergo horizontal linear displacement. Coaxially and at a certain distance from each other are the two throttle openings (16 and 29), serving as throttle seats and intended for the bypass line (13) and the return line ( 30), with the throttle opening (16) being assigned a throttling zone (15), serving as a drawer, the adjustment piston (14), and the throttling opening (29) being assigned a throttling zone (18), serving as a drawer, of the adjustment piston (14). With respect to the axis of movement of the adjusting piston (14), the throttle opening (16) is located at a certain axial distance from the throttle opening (29), so that the opening d 'throttle (16) has an axial distance, relative to the free end of the adjusting piston (14), greater than that of the throttle opening (29). The diameter of the throttle opening (16) is greater than the diameter of the throttle opening (29). The throttle zone (15) of the adjusting piston (14), which in the closed state seals the throttle opening (16) of the bypass pipe (13), continues conically towards the free end of the adjustment piston (14). To the conical throttling zone (15) is connected, towards the end of the adjusting piston (14), a cylindrical closing zone (17) having a smaller diameter. At the free end of the adjusting piston (14) is connected a throttling zone (18), pressing against the cylindrical closing zone (17), rounded and bevelled. The throttle opening throttle seat (16) cooperates with the conical throttle zone (15) in that, when the adjustment piston (14) is moved in the direction of opening (to the right in Figure 1), the bypass line (13) is released, and the bypass current (B) can flow in the direction of the arrows (B), through an envelope outlet (23) communicating with the agitator. In the direction of flow, downstream of the throttling zone (15) of the adjusting piston (14), the bypass current (B) passes through a bypass passage (20). The throttle seat, integral with the casing, in the region of the throttle opening (29), has an axial length greater than that of the throttle seat of the throttle opening (16). The distance between the throttle seat of the throttle opening (16) and the throttle seat of the throttle opening (29) is less than the reciprocal distance between the two throttle zones (15 and 18) of the adjustment piston (14), so that the throttle seat of the throttle opening (29) is adapted to the diameter of the cylindrical zone (17) of the adjustment piston (14). The return line (30) opens, in a mouth area (19), into the throttle opening (29), and is therefore open, in this mouth area (19), towards the adjusting piston. (14). The mouth area (19) is, in Figure 1, perpendicular to the plane of the drawing, from front to back.

 As soon as the adjustment piston has moved from the closed position according to FIGS. 1 and 2, in the direction of opening, under the effect of the electric motor (25), a bypass current (B) passes through the the annular space between the throttle zone (15) and the throttle seat of the throttle opening (16), so that the bypass current (B) passes through the throttle passage (20) and is sent to the agitator.

In this open position, the throttle opening (29) is still closed by the cylindrical zone (17) of the adjusting piston (14). If the adjustment piston (14) is still moved in the direction of the opening, the zone (17) arrives approximately at the axial height of the throttle seat of the throttle opening (16), which releases gradually the mouth area (19) and therefore the throttle opening (29) (see Figure 2).

Therefore, the return current can pass through the throttle opening (29) and be evacuated, passing through the throttle passage (21), to the return pipe (22) of the envelope part ( 2).

Thanks to the action of the regulator, the same advantages are achieved as those of the pressure regulator according to
G 94 09 680.5. Compared to this pressure regulator, the pressure regulator according to the invention however lacks a manually operated regulating element. Therefore, the maneuvering staff does not need to carry out pre-adjustments, which eliminates adjustment faults.

 It is further advantageous that the bypass is first fully open, before the pressure can continue to decrease through the return line (return current (R)). The discharge pressure acting on the bypass increases all the more that the piston is more open to decrease the spraying pressure by the return line, that is to say the greater the quantity of liquid flowing through the throttle holes (12). Part of the pressure drop is again compensated by a downward adjustment at the return piston, so that in each situation the maximum stirring power is available.

 Because two different throttling points are formed along its axial length, the adjustment piston (14) has a dual function. The beveled end of the constriction zone (18) makes it possible to obtain a flow characteristic that is to say linear.

The adjustment piston (14) therefore allows sensitive adjustment. The throttle zone (18) lags behind the throttle zone (15) in terms of its throttle function, so that one can also perform then a further reduction of the spraying pressure when the backpressure from the agitator is too large at the outlet (23) of the envelope. The return pipe (22) directly connects the return pipe (30) to the storage tank.

 In the direction of flow, behind the throttle passages (20, 21), the bypass line (13) and the return line (30) run parallel to each other, and approximately a vertical way down. In this zone, the bypass pipe (13) and the return pipe (30) are connected to each other by a cylindrical bushing, which has a horizontal axis parallel to the adjusting piston. The bushing is closed by a three-way valve (24), which can be continuously adjusted horizontally, parallel to the adjusting piston (14), using another electric motor (26). Due to its structure, the three-way valve essentially corresponds to the three-way valve already described in detail in G 93 01 935.1. Thanks to the three-way valve (24), which is in active communication both with the return pipe (30) and with the bypass pipe (13), it is possible to subdivide at will, thanks to a continuous adjustment, the bypass current (B) between the return to the tank and the return line to the agitator. There is a particular advantage here when, due to too high flow pressure in the bypass pipe, there is too intense a stirring effect.

 The bypass line (13) is, immediately after the filter cartridge (10), provided with a safety valve (27), which is kept closed by means of a compression spring (28). If there is too high an overpressure in the bypass line (13), this safety valve (27) opens, so that a flow current can fall directly into the return line going to the tank. storage, and the flow line will pass laterally against the throttle point formed by the throttle opening (29), the cylindrical zone (17) and the throttle zone (18) of the adjusting piston (14 ) (Figure 2). An overpressure in the bypass line (13) and a resulting opening of the safety valve (27) therefore always lead, regardless of the position of the adjusting piston (14), to a sufficient reduction in pressure. .

Claims (9)

1. Pressure regulator for an agricultural device  mobile for spraying a liquid contained in a  tank, having a flow compartment arranged  in the regulator envelope with a  spreading pipe connecting the compartment to  spray device and a line of  back connecting said compartment to the tank, a  bypass line connecting the compartment to a  agitator arranged in the tank, the  return and bypass pipeline each presenting  an adjustable choke point, characterized in that  that it includes means (14, 25; 6, 12) for controlling  simultaneously the two choke points (16, 29)  and make the regulation curve linear over a  specified area. 2. Regulator according to claim 1, characterized in that  that the throttle point (16) of the bypass (13) is  offset and ahead in the opening direction  with respect to the choke point (29) of the  return line (30). 3. Regulator according to claim 1 or 2, characterized  in that the liquid to be sprayed circulates in a  flow chamber (6), then in a  distribution (8), constituting elements of a  filter cartridge (10), a device for  retainer (12) being disposed between the two  chambers (6, 8) to increase the dynamic pressure  liquid flow, bypass line  being connected to an agitator in the room  of flow. 4. Pressure regulator according to claim 2,  characterized in that the adjusting device (14,  25) of each choke point (16, 29) has  a drawer (15, 18), the drawers being connected one to  the other in a rigid way to ensure a  common linear movement, the drawer (18) is  sealingly terminated at the seat  corresponding throttle (29), in the direction of  displacement, over a certain length which corresponds  approximately to the travel of the other drawer (15). 5. Pressure regulator according to claim 4,  characterized in that the two drawers (15, 18) are  arranged on a common adjustment axis, and one of the  drawers (18) present, in the opening direction,  a closing area (17), of a cross section  constant over the length of an axial stroke  perfectly defined, the closing area being  arranged at a certain axial distance from each other  drawer (15), which corresponds approximately  at the reciprocal distance of the two seats  throttling (29, 16). 6. Pressure regulator according to claim 5,  characterized in that the two drawers (15, 18) are  designed as different axial areas of a  continuously adjustable adjusting piston (14) which  running, is arranged horizontally in  the envelope (1, 2, 3, 4) of the regulator. 7. Pressure regulator according to one of claims  previous, characterized in that a three-way valve  tracks (24) is arranged in the area of each of the  outlets (23, 22) from the return pipe (13) and  of the bypass pipe (30) going towards the tank  storage said valve can be adjusted in  continuous, and being in active communication with  the two outputs (22, 23). 8. Pressure regulator according to claim 7,  characterized in that the adjustment axis of the valve to  three ways (24) is arranged parallel to the axis of  adjusting the adjusting piston (14). 9. Pressure regulator according to any one of  previous claims, characterized in that the  return line (30) and the line of  bypass (13) are located in the envelope (1 to 4) of the  regulator, in planes parallel to each other.