EA007695B1 - Piston pump - Google Patents

Abstract

The invention relates to a piston pump whose piston (4), via its upper and lower piston faces, delimits the working space inside the pump cylinder (5) on both sides. The working space (c) is joined via a lever system (19, 22, 25, 28, 31) to two force-guided inlet valves (14, 16) and two force-guided outlet valves (10, 12) that each alternately open and close for filling or discharging the working volume upon reaching both final positions of the piston. An additional working volume, which is reduced by the volume portion of the piston rod, is obtained by the piston being acted upon twice per working stroke as described by the invention thus nearly doubling the efficiency and resulting in a delivery flow with few pulsations. A small residual pulsation remains only from the short period of time during which the valves change from open to closed upon reaching both end positions of the piston inside the cylinder. According to the invention, the design of the piston pump makes it possible for two or more piston pumps to be synchronously operated by coupling their drive levers (31, 40) to a common piston rod (35) and that, in doing this, different stroke lengths can be set by modifying the lever ratios.

Description

The invention relates to a piston pump, comprising a housing and a piston bounding the working cavity in the pump cylinder by means of movements, according to the restrictive part of claim 1 of the claims. Advantageously, the invention relates to a piston pump for supplying and dispensing liquids of various kinds.

Piston pumps are well known in a variety of embodiments and serve the most varied purposes of delivery or drive (hydraulics). Known piston pumps use only one end surface of the piston to fill and displace the medium. Because of this, undesirable pulsation occurs, which in the case of a crank mechanism occurs for the suction stroke or the working stroke sinusoidally with its negative consequences for the allowable limiting suction head ΝΡ8 Η (# 1 Ро8111уе 1 и1е1 Neab) or for cavitation. In addition, for these piston pumps, the operation of the valve is purely independent, i.e., the suction depression and the working stroke pressure respectively open and close the check valves. As a result, the kinematics of the valve operation (closing delay angle) can be well controlled only in clean media. This causes, however, favorable pressure ratios of the installation system. Otherwise, overfilling or undersupply cannot be avoided. The problem is any kind of particles in a liquid medium, which adversely affect the tightness and, possibly, the mobility of the oscillating part of the valve. Particles have a different origin: preferably in the form of a contained substance (suspension) and undesirable in the form of “dirt” from the installation system or in the form of dust from abrasion of the piston seal. If unfavorable kinematics and / or particles in a liquid medium are unavoidable or are a desirable component, then such piston pumps cannot be used for quantitative dosing without changing the dosing flow. In addition, such pumps have to be designed in the valve zone rather complex, so that it is possible to use liquid media containing particles.

Waiye Egaiesch Wat 11 in the CB M08480A proposed, in the field of liquid pressure motors of pumps and internal combustion engines, to supply double-acting pistons to pump control with valves consisting of multiple levers, etc., namely one for each valve of the set, and to the named valve levers, etc. The cam mechanism, which they contain together and which is driven by the engine connecting rod, acts. Valve control comes from a cam mechanism consisting of a pusher or sliding part in combination with a connecting rod and urged to follow the groove, the upper surface of which consists of enlarged ends or thickenings of the rocking levers agreed to control the valves. Later, M. Ayig Sa81eai in EB 551600 A proposed a double-acting pump, in which the suction and discharge lines are opened or closed by a reciprocating pusher, with the plunger sliding along the disc or between two discs and intended to capture soft solids on its way or cutting them when passing. Against too high fluid pressure in very weak holes of the splines, the author proposes to place one or several springs between the sliding part and the piston rod. Both inventions have their intricate mechanics with many individual parts and, thus, many friction or wear surfaces. In addition, these proposed designs are very difficult to seal outside due to the multitude of sliding and friction surfaces. In ΌΕ 1177007 V (EEKA 8A), a double-acting piston pump is proposed, the intake and exhaust valves of which are hydraulically connected to the pistons, and their cylinders, respectively, are pairwise connected to each other via a closed pipeline. Whether this proposal has found practical application is rather improbable, since the small suction pressure of the intake valve or the force of its piston is not able to maintain the pump’s elevated pressure through the connected piston of the closing valve and therefore it will flow. In addition, this proposal has a lot of sealing places, which, in general, make the pump and its mechanism difficult to control.

The basis of the invention lies in the task of creating a piston pump of the type described above, which would operate with low pulsation and efficiently with only one piston, would contain forcedly operated suction and pressure valves and would have a simple compact design.

This problem is solved according to the invention due to the fact that the piston, with its upper and lower end surfaces, limits the working cavity in the pump cylinder on both sides and that the working cavity is connected by means of forcibly controlled inlet and exhaust valves that, when reaching both end positions of the piston, are alternately opened for filling working volume and closed to displace the working volume. Due to the double piston load for each stroke, an additional displacement volume reduced by a fraction of the piston rod volume is achieved, due to which the productivity almost doubles and / or a volumetric flow with small pulsation occurs. There is a small residual ripple due to the short period of time for changing the position of the valves from “open” to “close” upon reaching both end positions of the piston in the cylinder. By choosing a relatively large piston stroke relative to the valve opening angle, this residual pulsation can be minimized. The uniform flows of the pumped medium are achieved by means of a linear piston drive, for example, by means of a pneumatic cylinder, a hydraulic cylinder, a lifting magnet or a linear motor. According to the invention, it is further proposed that the intake and exhaust valves are connected by means of a lever system with a piston in such a way that

- 1 007695 reaching one end position of the piston, respectively, forcibly open one inlet and one exhaust valve and close the other intake and other exhaust valves, and when the other end position of the piston is reached, one inlet and one exhaust valve are closed and the other intake and other exhaust valves open. Thanks to this simple inventive solution with two inlet and two exhaust valves connected in pairs through a system of levers, the problem of two-sided loading of the piston is solved in a simple way. In particular, the piston pump does not require, due to this, double inlet and outlet channels, but only two valve chambers acting alternately as the suction cavity and the discharge cavity. Forced opening and closing of valves effectively prevents an erroneous flow of the pumped medium from the discharge nozzle to the suction nozzle or vice versa. According to the invention, moreover, it has been proposed that both intake and both exhaust valves are arranged symmetrically on their piston rod. Due to this, the problem of synchronization of valve movements with only two sealing points and a minimum of moving parts with only two rods is solved in a simple way. For forced alternate actuation of the intake and exhaust valves, it is further proposed that the rods with one side pass through the valves, the pump casing and the valve cover and at the end are connected by a rocker, one end of which is elongated and movably connects the rods to the discharge lever. According to the invention for supplying with a small pulsation and for regulating the volume supply, it is proposed that the cylinder is loaded by a piston, the rod of which passes through the cylinder, is connected to the pump cover by means of a driving lever and that this driving lever places the driving rod in a zone between its end points of rotation the other end is movably connected to the pressure lever. Mostly the drive is carried out by a pneumatic cylinder, which is equipped with an automatic switching device in both end positions of the piston. Due to this, the piston pump can also be used in hazardous areas. To ensure compactness and simplicity, further according to the invention, it is proposed that the pump casing has three boreholes lying on the same axis, one bore forming a working cavity, and both other bores with one transverse bore each form inlet and outlet channels in such a way that when the pump is in operation and the exhaust valves alternately to move the piston close and open the bores on one side. Due to this, the drive lever falls in the middle of the longitudinal axis of the pump, with the result that the design becomes simple and compact. The forced actuation of the valves according to the invention is due to the fact that the rods on the side facing the pump cover are threaded with a nut at the end, tightening or unscrewing which reduce or increase the distances between symmetrically arranged pairs of valves to adjust the gap. Valve seats can be made flat, conical or spherical. Minimum stroke with the required opening cross section of the valve is achieved with disc valves. For reliable sealing when pumping containing particles of liquid media and / or to reduce the accuracy of fit, the valves can be made with an elastic coating. According to the invention, the design of a piston pump ensures that two or more piston pumps can be operated synchronously by connecting their actuating levers with a common piston rod. For this, according to the invention, it is proposed that the pumps are connected mainly due to their vertical positioning one above the other in such a way that the drive rods can be connected directly to the underlying cylinder, as a result of which all pumps are arranged with a common drive. Where spatial conditions do not allow this, two or more pumps can also be located next to each other and be operated synchronously by the common connection of their piston rods. As a drive, a pneumatic cylinder with a trigger circuit has been proposed. However, any kind of linear drive or crank mechanism can be connected. In a crank mechanism, volumetric flow, however, is sinusoidal with negative consequences for permissible limiting suction pressure of 8. Regulation of the volume flow at a constant frequency of the stroke is solved, according to the invention, due to the fact that the discharge stroke can be changed individually for each associated pump by shifting its drive rod on its drive lever.

Below the invention is explained in more detail with the help of drawings depicting only one way of its realization, on which they represent:

FIG. 1 is a longitudinal section of a piston pump;

FIG. 2 - section AA of a piston pump;

FIG. 3 - two coupled piston pumps.

FIG. 1 shows a housing 1, 2, 3 of a pump with a cylinder 5, in which a piston 4 with a rod 7 sealed by a ring 6 is placed. With a rod 7 being sealed by a ring 6 and an epiploon 9, the rod 7 with its end facing away from the piston 4 passes through the pump body 3 and a valve cover 8 and is connected at the end by means of a yoke 19, one end of which is elongated and by means of a lining 22 movably connects the rods 11, 15 to the discharge lever 25. The discharge lever 25 mounted rotatably in the sleeves 23, 26, 27 of the slide, by rivodnoy rod 28 is connected to the driving lever 31. The driving lever 31 is fixed to the middle

- 2 007695 possibility of changing the point of application of the pressure lever 25 by means of a removable pin 32. Thus, the stroke of the piston 4 can be increased or decreased. The drive lever 31 is pivotally connected at one end with the cover 2 of the pump by means of a finger 34, and at the other end with a rod 35 by means of a finger 33. The rod 35 leaves the pneumatic cylinder 36, which is controlled with the possibility of spontaneous performance of constant reciprocating movement by it (trigger circuit ). Mostly this happens through two electromagnetic switches and two pneumatic valves for both end positions of the piston. The valve cover 8 is located at a distance from the base 29 by means of two distance rods 30. The yoke 19 is installed by means of the sleeve 21 in the middle of the middle of both piston rods 11, 15 on the elevation of the valve cover 8. At the 4 end facing the piston, the rocker arm 19 is slightly elongated and connected to swings by sleeves 23, 24 slip with lining 22. This is the elongation of the rocker arm 19, i.e. the distance between the force applied by the strap 22 and the swing point 21 of the rocker arm 19 should be chosen so that the effort required to actuate the rods 11, 15 through the swing points 18, 20 is noticeably lower than the effort required to move the piston. Otherwise, the pressure lever 25 would rotate only at the swing point 23, without moving the rods 11, 15.

FIG. 2 shows a section A-A of a piston pump in the middle of the intake valves 14, 16. In particular, this section shows the inlet channel, which, depending on the position of both symmetrically located valves 14, 16, is open or closed at the top or bottom.

FIG. 3 shows a fragment of two piston pumps connected one above the other of FIG. 1 with one common pneumatic cylinder 36 as a drive. The piston rod 35 of this pneumatic cylinder 36, through a rotating finger joint 37, leads an extension rod 38, which in turn, through a rotating finger joint 39, drives the drive lever 40 of the second piston pump. The drive lever 40 here has, between its centers of rotation 39.45, a groove containing a spindle with a spindle nut 43, on which the drive rod 44 is pivotally fixed. By rotating the handwheel 42, the spindle nut 43 is rotated and with it the drive rod 44 in the direction of the piston pump or handwheel 42. This changes the stroke of the coupled second pump, as a result of which the volume flow changed relative to the first pump can be adjusted with the same bore of the pressure cylinder.

Claims (6)

CLAIM 1. A piston pump with a housing (1, 2, 3), a double-acting piston (4), limiting the working cavity (a) by moving the pump cavity (5) and forced control of the valves to close the suction and discharge lines, characterized in that its body (1) has two bores (b, c) parallel to the cylinder (5), which, due to the transverse bores, serve as suction and discharge lines, respectively, and through which the rods (11, 15) pass, provided on both sides with ends with valves (10, 12, 14, 16), which By means of a lever system (19, 22, 25, 28), which is forcibly controlled and proportional to the force, connected to the piston drive, they cause, when the upper or lower end position of the piston (4) is reached, to close and displace the displacement, close open valves (12, 14) and opening closed valves (10, 16) or vice versa opening closed valves (12, 14) and closing open valves (10, 16). 2. The pump according to claim 1, characterized in that the rods (11, 15) on one side pass through the valves (14, 10), the pump housing (3) and the valve cover (8) and are connected at the end by a beam (19), one the end of which is elongated and through the lining (22) movably connects the rods (11,15) with the discharge lever (25). 3. A pump according to any one of claims 1 or 2, characterized in that the rods (11, 15) on the side facing the pump cover (2) have a thread with a nut (13, 17) at the end, screwing it in or out which decreases or increases the distance between symmetrically arranged pairs (10, 12; 14, 16) of valves for adjusting the clearance. 4. A pump according to any one of claims 1 to 3, characterized in that two or more piston pumps can be operated synchronously by connecting their drive levers (31, 40) with one common piston rod (35, 38). 5. The pump according to claim 4, characterized in that the connection of the pumps occurs mainly due to the vertical arrangement one above the other with the possibility of linking the drive rods (28, 44) directly to the underlying cylinder (36), as a result of which all the pumps are located with a common drive . 6. The pump according to claim 4 or 5, characterized in that the discharge stroke can be changed individually for each associated pump by displacing its drive rod (28, 44) on its drive lever (31, 40).