GB2082263A - Constant delivery pressure - Google Patents

Abstract

An electromagnetic pump has a throttle valve 36 downstream of its delivery valve 15, valve 36 being controlled by a plunger 39 subjected to the delivery pressure of the pump. Increase in pump delivery pressure causes valve 36 to throttle the pump output and maintain the delivery pressure constant. Fluid leaking into the chamber 42 is returned to the suction side by means of the return path 49. <IMAGE>

Description

SPECIFICATION Automatic pressure holding electromagnetic pump Summary of Invention In the technical field to which the present invention belongs, the electromagnetic pump causes the electromagnetic plunger and the pressure piston connected to the electromagnetic plunger to reciprocate by interrupted electromagnetic force of the electromagnetic coil and the pumping action is taken place by the suction valve and the discharge valve working together, and in order to keep the discharge pressure of the electromagnetic pump constant, so far there have been two systems.

The one system is a relief valve system for returning the extra outflow to the suction side, and the other system is a pressure sensitive control decompression valve system that senses the pressure at the discharge side to control the outflow by throttling the path at the discharge side.

The relief valve system is described in the specification of U.S. Patent No. 3,877,841 wherein the predetermined discharge pressure is set by returning the fluid to the suction side from the discharge side by means of the relief valve, but this pump always has a big constant piston stroke as the performance is set above required outflow on account of compensation of performance drop due to temperature rise of the electromagnetic coil and compensation of the discharge pressure against the fluctuation (primarily, +10%) of the input voltage, and as a result, it gives rise to vibration or noise.

Also, since the piston stroke was big, there was a need to provide a pressure accumulator for prevention of pulsation. Furthermore, in many cases, the relief valve is made of soft material such as rubber and the like in order to produce the performance as far as the structure is concerned, which results in greater influence of deterioration and limited service life. The breakage of the relief valve deteriorates the discharge pressure and in case the combustor is used, it results in incomplete combustion of the fuel.

Next, the pressure sensitive control decompression valve system is such that the decompression valve is provided in the path at the discharge side of the pump and the decompression valve is displaced by the discharge side pressure to control the outflow of the discharge side, whereby the piston stroke can be set to a required minimum in proportion to the discharge outflow, and the noise is small and no accumulator is required which are big advantageous points. The existing pressure sensitive control valve system can be roughly classified into the following two methods with respect to kinds of pressure receiving mechanism.

First, one method that uses the diaphragm as the pressure receiving mechanism has drawbacks which happen frequently such as loss of effect as the diaphragm because the used fluid saturates from the diaphragm due to the use of long hours, and is collected in the chamber at the housing side of the spring for adjusting pressure or the breakage of the diaphragm.

Second, the other method that uses the metal bellows as the pressure receiving mechanism has drawbacks such as cracks due to the use of long hours in the electromagnetic pump having greater pressure fluctuation or lack of practicality with regard to costs. Furthermore, as described in the foregoing, the diaphragm and the bellows which are the pressure receiving mechanism are broken due to the high pressure and the change of chemical physical property caused by the used fluid and deterioration due to the influence of physical fatigue caused by the pressure pulsation, and there was a danger of causing excessive outflow as a maximum performance of the electromagnetic pump is applied as it is to the nozzle which resulted in the high pressure. As described in the foregoing, there occur many various problems in the conventional adjustments of discharge pressure.

A first object of the present invention is to provide an automatic pressure holding electromagnetic pump to which the relief system based on the pressure sensitive control decompression valve system is applied, and is capable of keeping the discharge pressure constant on account of the change of the throttle amount of the decompression valve to the fluctuation of the discharge pressure.

A second object of the present invention is to provide an automatic pressure holding electromagnetic pump which has a structure that a gap between the pressure receiving plunger as the pressure receiving mechanism and a cylinder in which the plunger slides is determined on the basis of a minimum leakage of the fluid, and even if there is slight leakage from the gap thereof, the leaked fluid is returned to the suction side, and therefore a complete sealing between the pressure receiving plunger and the cylinder is not required, and as a result, the sliding resistance of the pressure receiving plunger can be made on extremely small, and the decompression valve for controlling the discharge amount of the discharge fluid can operate smoothly and sensitively.

Furthermore, a third object of the present invention is to provide an automatic pressure holding electromagnetic pump having excellent durability wherein the conventional diaphragm is not used as the pressure receiving mechanism, and the metal pressure receiving plunger sliding in the cylinder is used.

A fourth object of the present invention is to provide an automatic presure holding electromagnetic pump which can be manufactured with relatively moderate accuracy as a certain leakage from the gap between the pressure receiving plunger and the cylinder is ailowed, and as a result, the increasing of machining cost can be prevented.

A fifth object of the present invention is to provide an automatic pressure holding electromagnetic pump capable of changing the piston stroke of the piston by the discharge pressure and lowering the vibration and noise as the operation of required minimum can be taken place which matches the discharge amount.

A sixth object of the present invention is to provide an automatic pressure holding electromagnetic pump capable of improving a pulsation preventing effect together with the accumulator since the pump is provided with the pressure receiving mechanism.

Brief Description of Drawings Although these objects can be achieved by the present invention, the concrete embodiments will become obvious by referring to the attached drawings and the detailed description.

By the way, correction and modification related to the details of the structure is included in the claims to be provided hereinafter.

Figure 1 is an elevation of an automatic pressure holding electromagnetic pump in accordance with one example of embodiment of the present invention, Figure 2 is a cross section taken along a line A-A of Fig. 1, Figure 3 is a cross section taken along a line B-BofFig. 1, and Figure 4 is a cross section taken along a line C-C of Fig. 1.

Detailed Description of Invention The electromagnetic pump according to one preferred embodiment of the present invention is illustrated in Fig. 1 through Fig. 4, and an electromagnetic plunger (1) is caused to reciprocate by an electromagnetic coil (2) and the electromagnetic plunger ( 1 ) is supported in an electromagnetic plunger operation chamber (7) consisting of a guide case (5) and a pump proper (6) by an upper holding spring (3) and a lower holding spring (4), and this chamber (7) is separated into an upper spring chamber (7a) and a lower spring chamber (7b) by means of the electromagnetic plunger (1). A hole (8) is bored in the axial direction in the electromagnetic plunger (1), and the upper spring chamber (7a) and the lower spring chamber (7b) are communicated by the hole (8).

A piston (9) is integrally connected to the electromagnetic plunger (1), and is inserted into a cylinder (10). This cylinder (10) is disposed in a cylinder inserting hole (11) connected to the lower spring chamber (7b) by means of an elastic material (12). Also, the cylinder (1 ) is formed with a spring receiver ( 13) that receives the lower spring (4), and the spring force is applied to the cylinder (10) by means of the spring receiver ( 13).

A suction side check valve (14) and a discharge side check valve (15) are disposed in a connected valve seat member, and is inserted into a valve inserting hole (16) of the pump proper (6). The check valve (14) of the suction side is compressed and seated on a valve seat member (17) of the suction side by means of a spring (18), and said valve seat member (17) is connected to a member (20) provided with a strainer (19) at its one end, and a valve seat member (21) of the discharge side is connected to the other end. A check valve (1 5) of discharge side is compressed and seated on a valve seat member (21) of the discharge side by means of a spring (22), and a valve cylinder (23) holding the spring (22) is screwed to the valve seat member (21).

By the way, when the suction side check valve (14) and the discharge side check valve (15) are seated on the valve seat members (17) and (21), the seating surfaces tend to wear out so that members (24), (25) having high wear resistance are mounted on the valve seat members (17), (21), and can be seat thereon by means of the members (24), (25) having high wear resistance.

An 0 ring (26) is provided on an outer periphery of the valve seat member (21), and is seated in the valve inserting hole (16) to separate a pressure chamber (28) and a discharge chamber (29). The 0 ring (27) is provided on an outer periphery of the valve seat member (17).

A suction side coupling (30) is screwed to the pump proper (6), and the fluid is sucked through a suction hole (31) of the suction side coupling (30), and is led to the pressure chamber (28) from a conduit hole after passing the strainer (19). This conduit hole (32) is bored with a hole (34) communicating with a return path (49). A discharge plug (33) closes one of the valve inserting holes (16). A pressure adjusting mechanism (34) communicates with the discharge chamber (29), and is provided on a discharge side path (35) leading to a lower spring chamber (7b), and a decompression valve (36) is disposed on the path (35), and an area of the flow path is appropriately throttled by means of the decompression valve (36) and a throttle hole (36), and the outflow of the flowing fluid can be controlled.

The decompression valve 36 is disposed in a chamber (35a) of the upper stream side of the throttle hole (37), and the spring force of a spring (44) disposed in the chamber (35a) is compressed to the throttle hole (37) side by means of a spring receiver (55), and aiso the decompression valve (36) is influenced by the movement of a pressure receiving plunger (39) which is the pressure receiving mechanism by means of a rod (38), and the area of flow path of the throttle hole (37) is changed by the displacement of the pressure receiving plunger (39).

The pressure receiving plunger (39) is disposed slidably in a cylinder (40) formed on the pump proper (6), and is disposed in down stream of the throttle hole (37), and a chamber (35b) formed by a pressure receiving surface of the plunger (39) and the cylinder (40) is communicated with the lower spring chamber (7b) by means of a path (35c). An 0 ring (41) is formed on an outer periphery of the pressure receiving plunger (39), but leakage of small amount of the fluid is permitted through the gap formed between them.

A pressure adjusting spring (43) facing the pressure receiving plunger (39) of the cylinder (40) is housed in the decompression valve opposite chamber (42), and the pressure receiving plunger (39) is compressed in the direction of the decompression valve side by means of the pressure adjusting spring (43), and accordingly, the decompression valve (36) is shifted by resisting to a spring (44) having small load in the condition where the fluid is sucked into the pump, and a degree of opening with the throttle hole (37) becomes a maximum. Reference numeral (45) denotes a pressure adjusting screw, and when this screw is turned, the setting power of the pressure adjusting spring (43) can be adjusted, and the discharge pressure can be adjusted, and the adjusting position can be fixed by a lock nut (46).

Reference numeral (47) denotes a valve case and a valve seat (48) formed with the throttle hole (37) is provided at its front part, and when this valve case (47) is screwed to one end of the cylinder (40), it can be mounted at a desired position in the cylinder (40).

A return path (49) opens to the chamber (42) of the opposite side of the decompression valve of the cylinder (40) at its one end, and the other end opens to the suction side of the electromagnetic pump. Accordingly, the fluid gathered in the chamber (42) of the opposite side of the decompression valve of the cylinder (40) is returned to the suction side from time to time by means of the return path (49) on account of the negative pressure at the suction side.

An accumulator (5) is of a cylindrical shape and its accumulator case (51) is provided integrally with the pump proper (6), and is communicated with the lower spring chamber (7b). In this case (51), a diaphragm (52) is disposed, and a cap (54) is fitted by means of a diaphragm holder (53).

Accordingly, the diaphragm (52) is more strongly clamped to the pump proper (6) than the cap (54).

Reference numeral (55) denotes a spring interposed between the cap (54) and the diaphragm (52), and reference numerals (56) and (57) denote spring receivers.

A lower end of a fixed magnetic rod (58) is fitted in the upper part of the guide case (5), and is provided in the upper part of the electromagnetic plunger (1), and a path (59) communicating with a discharge outlet (64) is formed on its axial center.

An electromagnetic valve (60) is provided in a discharge coupling, and the discharge coupling (61) is screwed to the magnetic rod (58). The structure of the electromagnetic valve (60) is composed of a movable iron member (60a) and a rubber valve (60b), and the valve (60b) is compressed by a spring (62) by means of the movable iron member (60a), and is seated on a valve seat (63) to close a discharge outlet (64).

This electromagnetic valve (60) is moved by resisting to the spring (62) by its magnetic force when electric current is supplied to the electromagnetic coil (2) to open the discharge outlet (64), and the fluid is discharged from the discharge outlet (64) after passing the through hole (60c) formed on the movable iron member (60a) of the electromagnetic valve (60).

Anti-vibrating plates (66) for mounting the electromagnetic pump on the equipment are shown in Fig. 1 and Fig. 2, and are mounted in mounting holes (67) of the anti-vibrating plates (66) formed in horizontal direction at both sides facing the coupling (30) at the suction side in the lower part of the electromagnetic pump proper (6) by means of screws (68). The anti-vibrating plates (66) are formed with a bottom plate (69) for mounting the equipment to be installed, and holes (70) and (71) for mounting the equipment are bored on the bottom plate (69), and screws are inserted into the holes (70) and (71) so as to be mounted on the equipment. The anti-vibrating plates (66) have functions of mounting on the equipment and of absorbing the vibration to the electromagnetic pump.

In the foregoing construction, when the interrupted current flows to the electromagnetic coil (2), the electromagnetic plunger (1) is caused to reciprocate, and the piston (9) is caused to reciprocate accordingly, so that the pumping action is taken place by the check valve (14) at the suction side and the check valve (1 5) at the discharge side, and the fluid is sucked through the suction hole (31), and enters the path (35) through the suction side check valve (14) and the discharge side check valve (15), and passes the throttle hole (37) formed on the path (35) and enters the lower spring chamber (76) and passes the hole (8) of the electromagnetic plunger (1), and passes the path (59) of the magnetic rod (58), and the electromagnetic valve (60) is opened with the magnetic force of the electromagnetic coil (1) and the fluid is discharged through the discharge outlet (64).

The electromagnetic pump discharges the fluid of fixed pressure from the discharge outlet (64), and by any chance, if the pressure feeding power is increased, the pressure is increased between the nozzle and the pump chamber (28) by fluid resistance such as the nozzle, and the pressure receiving plunger (39) is displaced by resisting to the pressure adjusting spring (43), and this displacement amount is transmitted to the decompression valve (36) by means of the rod (38), and the decompression valve (36) is shifted in the direction of strengthening the throttling action, and the passing outflow is throttled by means of the throttle hole (37) and the decompression valve (36), and the supply to the nozzle side is limited, and the discharge pressure is adjusted automatically to a set pressure.By the way, when the throttling is effected by the decompression valve (36), the pressure in the pump chamber (28) is increased so that the stroke of the piston (9) becomes small, and the suction amount is adjusted to the same amount in proportion to the discharge amount.

Also, when the pressure from the discharge outlet (64) to the pump chamber (28) is decreased, a balance with the pressure adjusting spring (43) for compressing the pressure receiving plunger (39) is lost, and the pressure receiving plunger (39) is compressed by the pressure adjusting spring (43), and the decompression valve (36) is shifted in the direction of moderating the throttling action, and the discharge pressure for increasing the passing outflow is automatically adjusted to a set pressure. By the way, when the throttling action is moderated with the decompression valve (36), the pressure in the pump chamber (28) is lowered, and as a result, the stroke of the piston (9) becomes increased, and the suction amount becomes the identical amount in proportion to the discharge amount, and is adjusted to the increased amount.The adjustment of the discharge pressure is performed by turning the screw (45) for pressure adjustment, and the discharge pressure can be adjusted to an optional set pressure, but it is no doubt the maximum performance of the electromagnetic pump, namely, the pressure adjusting range within the maximum discharge pressure in each nozzle used.

Since the pressure receiving plunger (39) is slidable in the cylinder (40) and is loosely fitted, the fluid working on the pressure receiving plunger (39) flows through the gap formed with the cylinder (40) and is collected in the chamber (42) of the opposite side of the decompression valve, but as the negative pressure at the suction side is applied on the chamber (42), it is sucked and returned to the suction side of the electromagnetic pump so that there is no influence caused by the leaking fluid, and the pressure receiving plunger (39) can always operate sensitively. Moreover, since the elastic material (41) like 0 ring is interposed in the gap of the pressure receiving plunger (39) and the cylinder (40), there is an effect of improving the micro pulsation balancing effect.

The generation of the fluid cannot be avoided owing to the reciprocating motion of the piston (9), and the part can be absorbed by the pressure receiving plunger (39), but the pulsation can be absorbed by the accumulator (50) provided on the pump proper (6).

Claims (5)

1. An automatic pressure holding electromagnetic pump wherein a check valve at suction side and a check valve at discharge side are provided, and the reciprocating motion of the electromagnetic plunger of the electromagnetic coil and the piston is caused by the electromagnetic force of the electromagnetic coil,.

whereby the pumping action is performed the improved electromagnetic pump wherein a decompression valve for throttling the outflow flowing in the path at the discharge side is provided on the path, and the decompression valve is displaced by the pressure receiving plunger to which the pressure at the discharge side is applied, and the plunger is slidably provided in the cylinder, and a pressure adjusting spring is disposed in the chamber of the opposite side of the decompression valve facing the pressure receiving plunger of the cylinder, and a return path communicating with the suction side of the electromagnetic pump is formed in the chamber of the opposite side of the decompression valve, and the pressure is adjusted with the decompression valve, and the fluid leaking in the chamber of the opposite side of the decompression valve of the cylinder is returned to the suction side by means of the return path.

2. An automatic pressure holding electromagnetic pump according to claim 1 wherein an elastic material such as 0 ring is provided on the pressure receiving plunger.

3. An automatic pressure holding electromagnetic pump according to claim 1 wherein a valve seat on which a throttle hole is bored is provided on a valve case, and when the valve case is mounted on the cylinder, the valve seat is mounted at a desired position in the cylinder.

4. An automatic pressure holding electromagnetic pump according to claim 1 wherein the throttle valve is of spherical shape, and the throttle valve is of the rod fixed to the pressure receiving plunger, and its opening and closing are controlled.

5. An automatic pressure holding electromagnetic pump according to claim 1 wherein adjustment of the discharge pressure is performed by turning a pressure adjusting screw that changes the set power of the spring compressing the pressure receiving plunger.