CN87210070U

CN87210070U - Tandem metering pump unit

Info

Publication number: CN87210070U
Application number: CN 87210070
Authority: CN
Inventors: 黄小平; 张敏
Original assignee: Lishui Computer Application Research Institute Zhejiang Province
Current assignee: Lishui Computer Application Research Institute Zhejiang Province
Priority date: 1987-07-11
Filing date: 1987-07-11
Publication date: 1988-10-26

Abstract

The utility model discloses a tandem metering pump unit applicable to conveying liquid for batching, comprising a primary stage liquid sending pump and a partial metering pump connected in series. The two pumps are driven by the same power source. The metering pump is a driving capacity flow meter, driven by a retarding mechanism after decelerating. The flow of the liquid sending pump is a little larger than the discharge of the metering pump. A leakage channel is arranged between the outlet and the inlet of the liquid sending pump, making the internal leakage flow of the metering pump closed to zero. A signal generator is installed on the shaft of the liquid sending pump. The utility model has the advantages of simple device, high precision, high reliability, and high resolution, which can be used for liquid trade measuring in storehouses and shops with a microcomputer control system.

Description

Tandem metering pump unit

The utility model relates to a kind of dosing pump assembly that is used for quantitatively carrying liquid.

In the prior art, carry liquid quantitatively, generally adopt liquid delivering pump to carry liquid,, volume flow rate is converted into pulsed quantity, realize metering, control by control system by the signal-transmitting machine that is contained in the flowmeter rotating shaft with its volume of volume-displacement precision measuremnt.Obviously, quantitative precision depends on the precision that flowmeter measures basically.

For the volume-displacement of band signal-transmitting machine, the size of its resolution and volume constant, promptly when flowing through the per unit volume flow, how much relevant the pulse number that signal-transmitting machine sends is, and the volume constant is little, and then resolution is low.Because the manufacturing of signal-transmitting machine is subjected to the restriction of each side, causes its resolution to be limited in the corresponding scope.In addition, because there is pressure reduction in the flowmeter two ends, the leakage current in the flowmeter changes along with the variation of fluid viscosity, density.When small flow, the error in dipping of fluid is difficult to certain pattern correction especially.Above-mentioned reason makes this pump add the structure of flowmeter, when being used for quantitative delivery of small amounts of liquids, can't reach the measuring accuracy of pertinent regulations.

For the leakage current that makes volume-displacement is zero, the method that solves is to adopt driving volume-displacement (the following metering pump that all is referred to as) conscientiously, and makes it to work under the state that does not almost have pressure reduction.Someone has proposed a kind of feasible scheme: pressure differential detection mechanism is detected by the pressure reduction of PRESSURE PIPE to the metering pump two ends, send the signal that pressure reduction therewith is directly proportional, amplify through amplifier, drive actuating motor, finally regulate the rotating speed of metering pump, make before and after the metering pump pressure reduction almost nil and reach leakage current and approach zero purpose by servo-system.But because this scenario-frame complexity, cost is higher, makes to be difficult to this measurement structure be adopted by our said liquid meter pump-unit.

The purpose of this utility model, provide a kind of simple in structure, cost is low, is applicable to quantitative conveying liquid, and the dosing pump assembly of degree of precision is especially arranged when quantitative delivery of small amounts of liquids.

Design of the present utility model is, based on this dosing pump assembly that is used for quantitatively carrying liquid, its flow almost is the constant fact, when realizing that liquid delivering pump and metering pump are connected in series, realize feeding back naturally of flow equalization with a current by pass, reach the interior leakage current of metering pump and approach zero purpose; In addition, the mounting point with changing signal-transmitting machine promptly is installed in signal-transmitting machine in the high-revolving rotating shaft.The every do action of slow-revving metering pump rotating component once, the high rotating speed rotating shaft of proportional relation will turn over some commentaries on classics with it, make metering pump volume constant enlarge several times.

Fig. 1 is the structural representation of tandem dosing pump assembly.

Below with reference to Fig. 1 the utility model is described in detail.

Referring to Fig. 1, liquid-feeding pump (1) is connected in series composed cascade pump (11) with measuring pump (2). Consider that liquid-feeding pump (1) should be revolving, thereby it can be the impeller pump of vane type oil pump or positive displacement, and directly be driven by power source (4). Measuring pump (2) is driven after reducing gear (5) slows down by power source (4), mainly plays metering. If in the unit interval, as measuring pump (2) discharge capacity, so, the flow of liquid-feeding pump (1) should be slightly larger than the discharge capacity of measuring pump (2) the lifting rate of " bucket " (measuring room) that has fixed volume in the measuring pump (2). Between the outlet (8) and import (7) of liquid-feeding pump (1), one current by pass (9) is arranged, by regulating the screw (10) on it, to change current by pass (9) cross section, so that liquid-feeding pump (1) flow is greater than the part of measuring pump (2) discharge capacity---approximate the 1-15% of liquid-feeding pump (1) flow, return import (7) from this current by pass (9). Like this, along with the do action of measuring pump (2) tumbler, " bucket " in the pump is with liquid discharges that completely struggle against, and the pressure reduction at pump two ends is close to zero, and leakage current is also close to zero. In addition, because measuring pump is made relative low-speed running, therefore, signalling generator (3) is installed in the rotating shaft (6) with high-revolving liquid-feeding pump (1). When flowing through the unit volume fluid, the pulse that signalling generator sends is installed in the sort of situation on measuring pump (2) rotating shaft compared with it, and its volume constant has enlarged several times, and its multiple just equals the speed ratio of reducing gear (5).

The liquid delivering pump (1) of above-mentioned composition cascade pump (11), metering pump (2) and current by pass (9) can design in same housing, also can be independently splits, and be in aggregates through being linked and packed again.

Tandem dosing pump assembly with this structure, the influence of liquid body viscosity, variable density hardly of its volume constant, and have higher resolution.

The utility model has the advantages that simple in structure, low cost of manufacture, the measuring accuracy height, good stability is mixed Control System of Microcomputer, can carry liquid quantitatively, can be used for the liquid Trade Measures in warehouse, shop.

Provide an embodiment of the present utility model below with reference to accompanying drawing.

Fig. 2 is present embodiment pump body structure figure.

Referring to Fig. 2, the cascade pump of present embodiment (11) is connected in series by the gear pump (1) in the housing that coexists and ellipse garden gear pump (2) (driving ellipse garden gear meter) and forms. The flow of gear pump (1) is 11 liter/mins, and the discharge capacity of ellipse garden gear pump (2) is 10 liter/mins. On the outlet (8) of connection teeth wheel pump (1) and the current by pass (9) of import (7), an adjustable screw (10) is arranged. Cascade pump (11) is in when work, changes the cross section of current by pass (9) by adjustment screw (10), namely regulates discharge coefficient reaching gear pump two ends, ellipse garden pressure reduction close to zero, and final leakage current is close to zero purpose.

The overall structure of present embodiment is still referring to Fig. 1, and motor (4) directly drives first order pump---gear pump (1) in the cascade pump (11), and photoelectricity signal-transmitting machine (3) is contained on the running shaft (6).Motor (4) drives reduction gear box (5), and drives second level pump---the ellipse garden gear pump (2) of cascade pump (11) after slowing down.

The above embodiments are mixed temperature transducer, microcomputer and necessary control, executive component, have just formed a small-sized liquid quantitative pump-unit, and through actual measurement, its resolution is less than 0.1 milliliter, and quantitative error meets national measurement standard.

Claims

1, a kind of dosing pump assembly that can be used for quantitatively carrying liquid, its cascade pump [11] is made up of liquid delivering pump [1] and metering pump [2], it is characterized in that: power source [4] directly drives liquid delivering pump [1], and through reducing gear [5] deceleration drive metering pump [2], liquid delivering pump [1] flow is slightly larger than metering pump [2] discharge capacity, between the outlet [8] of liquid delivering pump [1] and the import [7] current by pass [9] is arranged, signal-transmitting machine [3] is installed in the rotating shaft [6] of liquid delivering pump [1].

2,, it is characterized in that liquid delivering pump (1) wherein is the rotor pump of vane type oil pump or positive displacement according to the described dosing pump assembly of claim 1.

3, according to the described dosing pump assembly of claim 1, it is characterized in that the screw that can regulate (10) is arranged on the current by pass (9) wherein, the 1-15% of liquid delivering pump (1) flow returns the import (7) of liquid delivering pump (1) from this current by pass (9).

4, according to the described dosing pump assembly of claim 1-3, it is characterized in that forming the liquid delivering pump (1) of cascade pump (11), metering pump (2) and current by pass (9) are in same housing.

5, according to the described dosing pump assembly of claim 1-3, it is characterized in that forming the liquid delivering pump (1) of cascade pump (11), metering pump (2) and current by pass (9), former is independently split, whole through being linked and packed again.