DE2353220A1 - Liquid dosing system with pumping device - has pump drive controlled according to required dosage per unit of time - Google Patents

Abstract

The pumping device is coupled to a hydraulic drive device, whose hydraulic circuit contains an excess pressure safety device. The dosage is adjusted by controlling or regulating the effective quantity of the hydraulic fluid. The dosage can be adjusted by controlling or regulating the working frequency of the hydraulic drive device. The piston of the pumping device is connected to the piston, capable of being loaded on both sides, of a hydraulic working cylinder, whose two chambers can be connected alternately to a hydraulic pump via a reversing slide. The working cylinder piston can have two steps on both sides.

Description

PATENT ADVOCATE
Dfpl.-Ing. Rudoif fvlöbus

Reutlingen / Wu rf f.
Hindenburgstr. 65 phone 34718

P 2261

! Company Wepuko-Hydraulik GmbH 7418 Metzingen

Max-Eyth-Str. 31

Dosing device for liquids

The invention relates to a metering device for liquids, with at least one pumping device, whose drive is controlled or regulated as a function of the dosing quantity required per unit of time. Such metering devices are used primarily in the chemical industry for controlled feeding used by catalyst fluids or buffer fluids.

Dosing devices known to date (unfortunately not known from literature) consist of at least a piston pump, the piston stroke length being changed to control the metered quantity. The piston is preferably operated via a crank drive, and either the point of application is used to adjust the piston stroke a connecting rod on a cam disc

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pushed or, the leverage in a connecting linkage between the crank disk and changed the piston. The Yerstellvorrichtungen required for this have a complicated one mechanical structure, through which the metering device is noticeably more expensive. Also are these facilities are relatively prone to failure and require electric servomotors, which are used in many applications special safety precautions due to their relative proximity to the medium to be dosed, such as bunkering the entire metering device, make necessary.

The control of the known metering devices a change in the piston stroke leads to small delivery rates to the disadvantage that the piston seal does not have adequate lubrication because of the short piston travel receives and runs dry. In addition, with many substances in short-stroke operation of the piston pumps, outgassing can occur or a segregation of the liquid contained in the cylinder space of the pump can occur. The occurring gas pockets form compressible areas in the cylinder chamber that are able to absorb short piston thrusts, so that there is no pumping action. This risk also exists with these pumps if the piston stroke is in the magnitude of the stroke of the closing elements of the non-return valves comes through which the Kolbendosierpnmpe promotes ala in the feed line of the dosing liquid.

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The invention is based on the object of creating a metering device which, while avoiding the above-mentioned disadvantages also "with small Safely promotes dosing quantities and their adjustability both at lower cost as well while avoiding electrical parts and those that are hazardous to the environment Overpressure valves in the media area is accessible.

The task at hand is with a metering device of the type mentioned above is achieved in that the pumping device is equipped with a hydraulic drive device is coupled, an overpressure safety device is arranged in the hydraulic circuit of the drive device, and that the setting of the dosage either by a control or regulation of the effective amount of the hydraulic drive means or by a Control or regulation of the working frequency of the hydraulic drive device takes place.

By using a hydraulic drive device, electrical drive and control parts become prevented in the area of the medium to be dosed, so that even highly explosive media are conveyed by means of the metering device without additional protective devices can be. A fully effective overpressure protection of the line for the medium to be dosed

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is achieved by the overpressure safety device in the hydraulic circuit of the drive device. S ¹ No overpressure valves need to be provided for the liquid to be dosed, which, in the case of aggressive "liquids, can cause major problems with regard to the discharge of the medium exiting through these valves.

The pumping device can be a piston pump in a conventional manner, the cylinder chamber of which has one-way valves is placed in the line of the liquid to be dosed. The hydraulic drive device for Such a pumping device can expediently consist of a hydraulic drive cylinder which can be acted upon on both sides Pistons exist, and this drive device is via a reversing valve with a hydraulic pump coupled. The hydraulic pump can advantageously operated at constant speed, and the control of the effective and promoted by the hydraulic pump Amount of hydraulic drive means can either be about one depending on the desired Dosing quantity adjustable three-way flow regulator or by using a pump with variable flow rate can be achieved. This has the great advantage that the piston pump always has more of the full piston travel or is driven through less quickly, so that in the cylinder chamber of the piston pump of the pumping device no

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Dead space is created in which the medium to be dosed could outgas or separate. Even the closing elements of the one-way valves are lifted off with certainty and the valve seats are flushed clear, while in the short-stroke operation of conventional piston metering pumps, the closing elements of the one-way valves can get into a rapid interplay in which the liquid to be dosed! ! Solid particles can be hammered onto the valve seats and impair the valve function.

Advantageously, the reversal of the piston of the hydraulic drive device by a automatic switching of the reversing slide connected between the drive cylinder and the hydraulic pump causes. The control of the reversing slide is also expediently carried out hydraulically, with the Drive cylinder can be provided with a stepped piston and on both-cylinder chambers end position pressure chambers can be connected, each via a hydraulic switching line with one of the Switching pressure chambers formed at the two slide ends of the reversing slide are connected, the switching lines can expediently each via a one-way valve (non-return valve) with the connecting line of the associated cylinder chamber be connected. With such a reversing device, the advantage is achieved

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that the reversing slide after switching in his new position by pressure feedback from the drive cylinder against automatic switching by flow forces is secured.

However, a diaphragm pump can also be used as the pumping device, which has a pump chamber placed in the line of the liquid to be dosed via one-way valves and a drive chamber which is separated from the pump chamber by the diaphragm and which is connected to a hydraulic pump. The hydraulic pump iB.t coupled to a timer device which determines the operating frequency ¹ of the hydraulic pump and hence also the operating frequency of the diaphragm pump in dependence on the desired metering quantity. A reversing pump is expediently used as the hydraulic pump, which works alternately in boxer operation on two diaphragm pumps, with its two connections each being connected to the drive chamber of a diaphragm pump and via a one-way valve to a drive medium reservoir. The clock generator device controls at least the reversing frequency of the hydraulic pump or both the reversing frequency and the degree of adjustment of the hydraulic pump as a function of the desired dosing amount.

Even when using Koibendoa pump. «Iu the pumping device has the advantage that by

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a common hydraulic drive device two metering pumps operated in opposed directions in boxer operation can be that see strength-wise support each other. '.

The hydraulic pumps with their electric drive unit can be at a safe distance from the metering pump devices be arranged as the hydraulic connecting lines to a drive cylinder or leave a great deal of leeway for diaphragm pumps in terms of their length. Leave the dosing devices are also significantly cheaper than conventional dispensing devices and dispensing devices Put together practically completely from commercially available individual parts.

Details of the invention emerge from the following description in conjunction with the drawing, on the various embodiments according to the invention trained metering devices are shown schematically.

Show in detail:

Pig. 1 shows a first exemplary embodiment of a metering device with a hydraulically operated one EoTben metering pump;

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Fig. 2 with a second embodiment

a hydraulically operated piston metering pump;

Pig. 3 shows an embodiment of a metering device with two diaphragm metering pumps.

1 shows a metering piston pump 10, the cylinder space 11 via check valves 12 and 13 into the delivery line for the liquid to be dosed. The piston 14 of the metering piston pump 10 is via a Coupling 15 is connected to the piston rod 16 of the piston 17 of a hydraulic drive cylinder 18. The piston 17 of the drive cylinder 18 is on both sides can be acted upon and divides the cylinder space into two cylinder chambers 19 and 20. With the piston rod 21, the Pistons of a second metering piston pump can be connected.

The two cylinder chambers 19 and 20 of the working cylinder 18 are over lines 22 and 23 and over a reversing valve 24 alternately connected to a delivery line 25 and a return line 26. In the delivery line 25 is from a hydraulic pump 27 via an adjustable three-way flow regulator 28 Drive fluid conveyed. The hydraulic pump 27 is operated by means of an electric motor 29 operates continuously and provides a constant

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! Delivery rate per unit of time. The amount of im Three-way flow regulator 28 in the overflow line 30 and further branched off into the return line 26 Drive means is not shown in more detail depending on the desired dosage Way regulated. The return line 26 leads in a reservoir 31, into which the suction line 32 of the hydraulic pump 27 also opens. Between the A pressure relief valve 34 is connected to the pressure line 33 of the hydraulic pump 27 and the return line 26.

The reversal of the reversing slide 24 is carried out via, for example, hydraulic limit switches 35 and 36 causes, which acts on a stop 37 attached to the coupling 15 and the over with dashed lines Lines drawn switching pulse lines 38 and 39 with switching chambers, not shown, to the Slide ends of the reversing slide 24 are connected.

In Pig.1 the drive device is in a switching position shown in which the piston 14 of the metering piston pump 10 in the direction of the registered Arrow 40 is moved and via the check valve 12 sucks dosing liquid into the cylinder chamber 11. The amount of drive fluid used by the pump 27 is supplied into the delivery line 25 via the three-way flow regulator 28, depends on the position

• 10

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of the three-way flow regulator 28, which is regulated as a function of the desired dosage per unit of time or controlled. Of the amount reaching the drive cylinder 18 via the reversing valve the adjustment speed depends on the drive fluid per unit of time of the piston 17 and thus the adjustment speed of the piston 14 of the piston metering pump 10 from. Correspondingly, during the stroke movement of the piston 14, the amount per unit of time is also that of the Check valve 13 promoted from the cylinder chamber 11 Amount of dosing liquid. Occurs in the dosing liquid line an impermissible overpressure, this overpressure also acts on the piston 14 of the metering piston pump 10. This pressure is transmitted in the ratio of the effective piston areas via the piston 17 of the Drive cylinder 18 on the hydraulic drive part of the metering device and thereby ultimately leads to actuate the pressure relief valve 34 and to reduce the pressure in the hydraulic drive part. Through this there is also a pressure reduction in the dosing liquid line, which is effective against overpressure via the overpressure valve 34 located in the hydraulic drive circuit is secured. The piston movement 14 is reversed from the delivery stroke to the suction hub via the limit switch 36 only in an end position of the Tolbens 14 of the dosing piston pump 10 when practically all of the dosing liquid present in the cylinder chamber 11 Via the check valve or one-way valve 13 into the

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Dosing line has been promoted.

In Fig. 2 are those corresponding to the circuit according to Fig. 3 Parts identified with the same reference numerals. The embodiment according to Pig. 2 differs from the Embodiment according to]? Ig.1 by saving a current regulator and using a hydraulic pump 41 with adjustable! Delivery rate, whereby the 3? Delivery rate adjustment this pump depending on the desired amount of dosing liquid per unit of time he follows. In addition, in this embodiment, a Drive cylinder 42 is provided with a stepped piston 43 with hydraulic end position damping, which also controls the reversal of the reversing slide 24 causes. The piston

43 of the drive cylinder 42 has a first step 43a and a second step on both sides 43b provided. With the second step 43b, the piston 43 can be at the ends of both cylinder chambers 44 and 45 connected switching pressure chambers 46 and 47 immerse, from which hydraulic switching pulse lines 48 and lead to switching chambers, not shown and acting on the ends of the slide valve part 241. The connecting lines 50 and 51 for the two cylinder chambers

44 and 45 open into the end areas of these cylinder chambers, where they are covered by the first steps 43a of the piston 43 in their end position for piston damping can. Between the switching pulse lines 48 and and the associated cylinder connection lines 50 and

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a check valve 52 and 53 is arranged in each case .

In the embodiment according to FIG. 2, the adjustment speed of the piston 43 of the drive cylinder 42 and thus the adjustment speed of the piston 14 of the metering piston pump 10 is determined by the delivery rate setting of the adjustable hydraulic pump 41. If the piston 43 of the drive cylinder 42 approaches an end position, one of its second steps 43b plunges into it the switching pressure chamber 46 or 47 and generates a switching pressure there, which is transmitted via the switching pulse line 48 or 49 acts on the slide part 241 and thus causes the reversing valve 24 to be switched over. In the subsequent movement of the piston 43 in the other direction, the slide 241 remains above one of the check valves 52 or 53 under pressure, so that the reversing slide 24 is always in its instantaneous Switch position is secured.

In the embodiment according to Pig.3 there are two diaphragm metering pumps 60 and 61 are provided, both of which are driven alternately by a reversing pump 62 in boxer operation which in turn is driven by means of an electromagnet 63. Both diaphragm metering pumps 60 and 61 each have a pumping chamber 64 and 65, respectively, via linear valves 66 and 67 and 68 and 69, respectively are placed in a line for the dosing liquid.

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The pump chambers 64 and 65 are connected to a drive chamber through the diaphragm 70 and 71 of the metering diaphragm pumps 72 and 73 separated, each connected via connecting lines 74 and 75 to one of the two connections of the Reversing pump 62 are connected. From the two connecting lines 74 and 75 each lead a Kaansaugleitung 76 or 77 (to cover the amount of leakage) via a check valve 78 or 79 into a liquid reservoir 80. The drive chambers 72 and 73 of the two diaphragm metering pumps 60 and 61 are also via lines 81 and 82 and a shuttle valve 83 with a common Pressure relief valve 84 connected.

The reversing pump 62 is equipped with a pump control device 85 coupled via a programmer 86 as a function of the desired amount of dosing liquid is controlled per unit of time. The program unit can be constructed, for example, as a cam switch unit. With it, the frequency of the reversal of the pump 62 and thus also the operating frequency of the two diaphragm metering pumps 60 and 61 controlled. In addition, the adjustment strength and thus the delivery rate of the reserve pump 62 can be controlled as a function of the desired delivery rate. Through this the deflection strength of the diaphragm 71 and thus the stroke volume of the metering diaphragm pumps can also be changed.

Auen in the embodiment according to Pig.3 have an effect unwanted overpressures in the dosing liquid line

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Via the membranes 70 and 71 onto the drive part Dosing device and bring the pressure relief valve 84 to respond; also, here is an overpressure safety device la drive part of the metering device reached.

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Claims (1)

P 2261 - 15 - Pa t enta η proverbs Dosing device for liquids, with at least a pumping device, the drive of which is dependent on is controlled or regulated by the dosing quantity required per unit of time, characterized in that that the pumping device (10) is coupled to a hydraulic drive device (18, 42) in the hydraulic circuit the drive device an overpressure safety device (34) is arranged and the setting the dosing amount by controlling or regulating the effective amount of the hydraulic drive means he follows. 2 «, dosing device, for liquids with at least a pumping device, the drive of which is dependent on is controlled or regulated by the dosing quantity required per unit of time, characterized in that that the pumping device (60,61) is coupled to a hydraulic drive device (62), in Hydraulic circuit of the drive device an overpressure safety device (84) is arranged and the setting of the dosage by a controller or the working frequency of the hydraulic drive device is regulated. (Pig. 3) - 16 - 509819/0049 P 2261 - 16 - 3. Dosing device according to claim 1, characterized in that as a pumping device in per se known Way, a piston pump (10) with one-way valves (12,13) in the line of the to be metered Liquid-placed cylinder chamber (11) is provided, and that the piston (14) of the pumping device connected to the piston (17.43) of a hydraulic drive cylinder (18.42) that can be acted upon on both sides whose two cylinder chambers (19.20; 44.45) are alternately connectable to a hydraulic pump (27, 41) via a reversing slide (24). 4. Dosing device according to claim 3, characterized in that the hydraulic pump (27) with a constant Speed is operated, has a non-adjustable body volume and a function adjustable three- way flow controller (28) with the reversing slide (24) connected is. 5. Metering device according to claim 3, characterized in that the hydraulic pump (41) with a constant Speed is operated and a device for adjusting the delivery rate as a function of the Has the desired dosage. 6. Dosing device according to at least one of claims 3 to 5, characterized in that the Umstemer- -17- 509819/0049 P 2261. _ 17 - slide (24) with a depending on the Piston position of the pump device (10) influenced switching device. (35-37) is coupled, 7. Dosing device according to at least one of the claims 3 to 5 »characterized in that the drive cylinder (4-2) is provided with a stepped piston (43) is and to both cylinder chambers (44,45) switching pressure chambers (46,47) are connected, each via a hydraulic switching impulse line (48,49) with in each case one of the two ends of the slide part (241) of the reversing slide (24) formed Switching pressure chambers are connected. 8. Dosing device according to claim 7, characterized in that the switching pulse lines (48,49) each Via a one-way valve (52> 53) with the connecting line (50,51) of the associated cylinder chamber (44,45), are connected. 9. Dosing device according to claim 7 »characterized in that the piston (43) of the drive cylinder (42) is double stepped on both sides (steps 43a, 43b). 10. Dosing device according to claim 2, characterized in that the pumping device as a diaphragm pump (60,61) with a one-way valves (66,67 ; 68,69) in the • line of the liquid to be dosed pumping -18- 509819/0049 chamber (64,65) and with one of the pumping chamber drive chamber (72, 73) separated by the diaphragm (70, 71) and connected to a hydraulic pump (62) is, is formed, and that the hydraulic pump (62) is coupled to a program unit (86), das'die Working frequency of the hydraulic pump (62) and thus of the diaphragm pump (60,61) depending on the desired dosing amount. 11. Dosing device according to at least one of the claims 1 to 10, characterized in that the drive device in boxer operation on two pumping devices acts. ■ ^. Dosing device according to claim 10 and 11, characterized in that that the hydraulic pump (62) acting as a drive device is designed as a reversing pump, Both of these connections are connected to the drive chamber (72, 73) of a diaphragm pump (0.61) and via a one-way valve (78,79) are connected to a drive means reservoir (80), and the program mechanism (86) thereof The reversing frequency of the hydraulic pump (62) controls. ^. Dosing device according to claim 12, characterized in that that the program unit (86) both the reversing frequency and the Yerstellgrad the hydraulic pump (62) controls depending on the desired dosage. 509819/0049