JPH0341098Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of an electromagnetic pump used for fluid feeding, and aims to simplify the structure and improve pump performance.

By the way, a normal electromagnetic pump has a structure in which a free piston-shaped plunger housed in a cylinder is provided with a fluid passage and a check valve for suction, and a check valve for discharge is provided on the discharge side of the cylinder. .
For this reason, the structure of the plunger part is particularly complex and the manufacture of this part is therefore very complicated.

In addition, in this type of pump, in order to easily open the suction and discharge check valves even with a small stroke of the plunger, the check valves are moved in the closing direction. The valve spring for energizing must have an extremely small spring constant. For this reason, it is difficult to avoid instability in the operation of each check valve, and in particular, the check valve provided on the plunger side is particularly susceptible to instability because the plunger repeats rapid reciprocating motion, and the pump This has a large negative impact on performance.

Therefore, attempts have been made to reduce the number of check valves in order to address these problems and minimize the instability factors that affect pump performance. For example, in Japanese Utility Model Application Publication No. 55-125982, a constricted portion is provided in the fluid passage of the plunger to perform the same function as a check valve, thereby reducing the number of check valves to only one on the discharge side. An electromagnetic pump has been proposed. However, in this pump, the narrowed part provided in the fluid passage of the plunger has a diameter of 0.4 mm.
It is necessary to form such a small hole with a diameter of ~0.6mm (in an experiment using No. 1 kerosene with a diameter of 0.8mm, the check valve function did not occur). The process of directly drilling a hole in a metal material requires extremely advanced processing technology, so it is inevitable that manufacturing will be troublesome.

The electromagnetic pump according to the present invention addresses the above-mentioned conventional circumstances, and in order to simplify the structure and improve the pump performance, the electromagnetic pump according to the present invention has improved the structure of a part of the cylinder, and also has a fluid passage from the plunger. The plunger is made into a simple block with a solid interior by eliminating the check valve and the minute space required to reciprocate the plunger between the outer peripheral surface of the plunger and the inner peripheral surface of the cylinder is used as a fluid passage. At the same time, it also functions as a substantial check valve, and is constructed so that only one check valve, which requires a valve spring, is required on the suction side or the discharge side. Hereinafter, an embodiment shown in the drawings will be described in detail.

In the figure, 1 is the cylinder of the electromagnetic pump,
It is composed of a thin-walled cylinder pipe 2 and cylinder plugs 3 and 4 that are fitted and fixed to both ends of the cylinder pipe 2. The cylinder pipe 2 mentioned above is made of a non-magnetic material, and the cylinder plug 3 on the suction end side is also made of a non-magnetic material, but the cylinder plug 4 on the discharge end side is made of a ferromagnetic material and is thinner than the cylinder inner diameter. It has a projection 5 and is inserted deeply into the cylinder pipe 2. Reference numeral 5' denotes a through hole formed in the protrusion 5 at the base of the plug 4 in the diametrical direction. Reference numeral 6 denotes an additional ring which is screwed to a position near the suction end on the outer periphery of the cylinder pipe 2, facing the projection 5, and is also made of a ferromagnetic material and is movable in the direction of the cylinder center line. ing. A plunger 7 in the form of a free piston is housed within the cylinder 1, and this plunger is a solid lump-like body, for example, spherical as shown in FIG. However, a short cylindrical plunger 7' as shown in FIG. 3 may be used. In any case, this plunger 7 or 7' is lightly pressed by retaining springs 8 and 9 from both ends inside the cylinder 1, so that
It is elastically held in the middle near the tip of the protrusion 5 described above, and is capable of reciprocating in the direction of the cylinder centerline with a minute gap between it and the cylinder inner peripheral surface that is difficult to illustrate. There is. Reference numeral 10 denotes a suction passage passing through the cylinder plug 3 on the suction end side, and communicates the suction port 12 of the mouthpiece 11 fitted to the plug into the cylinder 1, and 13 is a suction passage attached to the suction port 12. filter. Reference numeral 14 denotes a discharge passage passing through the cylinder plug 4 on the discharge end side, the inner end of which opens into the cylinder 1 through a through hole 5' formed at the base of the protrusion 5, and the outer end serving as a discharge port 15. It is opened. The passage 5' is not formed in the axial direction as in conventional electromagnetic pumps of this type, but is formed at the base of the protrusion 5 between the protrusion and the inner wall of the cylinder 1. This is to prevent air from accumulating, which would cause instability in the flow rate. However, the check valve that should be provided in the above-mentioned cylinder 1 is only on either the suction side or the discharge side, and in the illustrated example, the check valve is disposed on the suction side. That is, this check valve 16 is located in the suction passage 10 and is seated on a valve seat 17 provided on the mouthpiece 11 on the side of the suction port 12.
It is energized by a valve spring 18 with an extremely small spring constant. Reference numeral 19 denotes an electromagnetic coil wound around a bobbin 20, which is held by a yoke 21 so as to surround the outer periphery of the cylinder 1. The yoke 21 is made of a ferromagnetic material and has a U-shaped side surface.
At 23, it is fitted into the discharge side cylinder plug 4 and the additional ring 6, and is fixed to the outside of the cylinder 1 by screwing the rings. Further, this yoke 21 is provided with mounting protrusions 24, 24 on both sides of either the upper or lower plate-shaped portion, that is, the lower plate-shaped portion in the illustrated example, which extend laterally. It also serves as a mounting bracket for the entire pump, and can be fixed to the pump mounting seat 27 with the screws 26 passed through the screw holes 25 of each of these protrusions, eliminating the need for special mounting brackets found in conventional products. It's getting old. 28 is a drive circuit that supplies the required drive power A to the electromagnetic coil 19 in the form of an intermittent current;
Reference numeral 29 denotes a temperature compensating element for correcting a decrease in the pump discharge amount due to a rise in the temperature of the electromagnetic coil 19. For example, a thermistor is used. The temperature detection signal B is embedded in the coil or attached to the surface of the coil as shown in the figure.
is applied to the drive circuit 28.

In the electromagnetic pump configured as described above, if current is not currently flowing through the electromagnetic coil 19, the plunger 7 will remain stationary near the tip of the protrusion 5 on the cylinder plug 4 on the discharge end side by the holding springs 8 and 9. I'm forced to. In this state, the electromagnetic coil 19
When a current flows through the coil, the coil is excited and a magnetic force is generated that uses the yoke 21 as a magnetic path and the cylinder plug 4 on the discharge end side and the additional ring 6 on the suction end side as magnetic poles. The protrusion 5 of the plug 4 near the is pulled against the holding spring 9, and moves forward from the rest position to the discharge side, albeit with a slight stroke (second,
(Status shown in Figure 3). Furthermore, when the current flowing through the electromagnetic coil 19 runs out, the plunger 7 is moved by the holding spring 9.
It is pushed back and returns to its original resting position.

However, when the plunger 7 moves forward, the pressure in the cylinder 1 decreases on the suction side of the plunger and increases on the discharge side. Further, when the plunger 7 retreats, the pressure within the cylinder 1 increases on the suction side of the plunger and decreases on the discharge side. Therefore, in the illustrated example, the check valve 16 provided on the suction side
is opened when the plunger 7 moves forward and closed when the plunger 7 moves backward.

On the other hand, the forward movement of the plunger 7 is due to magnetic force, and the backward movement is due to the spring pressure of the retaining spring 9, so its forward speed is extremely fast, whereas its backward speed is much faster than its forward speed. It's late.

Therefore, when the plunger 7 retreats, the fluid whose pressure is increased on the suction side of the plunger in the cylinder 1 can relatively easily pass through the small gap between the outer peripheral surface of the plunger and the inner peripheral surface of the cylinder. Therefore, it flows toward the discharge side from the plunger, but
Conversely, when moving forward, the fluid whose pressure is increased on the discharge side of the plunger is extremely difficult to pass through the above-mentioned minute gap, and therefore almost never flows back to the suction side. In other words, this minute space is a fluid passage from the suction side to the discharge side within the cylinder 1, and at the same time, it functions similar to a check valve in relation to the forward and backward speed of the plunger 7. .

However, when comparing the embodiment shown in FIG. 2 in which a spherical plunger 7 is used with the embodiment shown in FIG. The length of the passage is
The former is shorter and the latter is longer. Therefore, in terms of the ease with which fluid passes from the suction side to the discharge side, the embodiment shown in Fig. 2 is superior, but in terms of the ability to prevent backflow from the discharge side to the suction side, the embodiment shown in Fig. 3 is better. This embodiment is better. Therefore, in both embodiments, there is almost no difference in the amount of discharge from the discharge port 15.

By the way, if the above-mentioned minute interval is within the range necessary for reciprocating the plunger 7 or 7', it is possible to allow the fluid to pass through and prevent the fluid from flowing backwards as described above. The width and narrowness of the tube affects the above-mentioned discharge amount; if it is too wide, the ability to prevent fluid backflow will decrease, and if it is too narrow, the amount of fluid passing through will decrease, and in either case, the discharge amount will be reduced. Therefore, when putting it into practical use, in order to maximize the discharge amount, the above-mentioned interval 〓
It is desirable to strictly select the width and narrowness of the area to a certain extent. Furthermore, this minute interval should be determined by taking into consideration the viscosity of the fluid to be passed.
The larger the viscosity of the fluid, the wider the gap must be. For example, we conducted an experiment using No. 1 kerosene according to JIS-K2203, and found that if the outer diameter of the spherical plunger 7 is set to 5/16" (approximately 7.94 mm) in the embodiment shown in Fig. 2, then the inner diameter of the cylinder should be When the plunger diameter is increased by 0.8 to 1.2%, the optimum distance is 0.064 to 0.095 mm (in this case, the distance is 0.064 to 0.095 mm), and if the distance is 0.095 mm, the electromagnetic pump has a diameter of 3000 mm. As a result of continuous operation for hours,
The electromagnetic pump worked normally. In addition, in the embodiment shown in FIG. 3, the outer diameter of the cylindrical plunger 7' is
8mm, and if the length is determined to be within the range of 1.5 to 2.5 times the diameter, then the minute distance when the cylinder inner diameter is increased by 1.5 to 2.0% of the plunger outer diameter (in this case, the distance is the diameter) (0.075 to 0.16 mm per minute)
is optimal, and the distance is 0.16mm, and the same value is 3000.
As a result of continuous operation for hours, the electromagnetic pump operated normally in this case as well. Of course, the viscosity of a fluid is easily affected by temperature, and therefore, even for the same fluid, the discharge amount varies depending on the temperature. However, the correlation between viscosity and temperature is not linear and varies considerably depending on the type of fluid. For example, with the above No. 1 kerosene, when the plunger outer diameter and cylinder inner diameter are determined as above, if the oil temperature is -10°C or higher, the kinematic viscosity of the kerosene is 2.7 cst or less, so the discharge There is almost no effect on the amount, but when the oil temperature drops to -20℃, the kinematic viscosity increases rapidly.
Since it becomes about 3.5cst, the discharge amount decreases by 15-20%. Therefore, it is best to select the above-mentioned minute interval experimentally within the range necessary for reciprocating the plunger 7 or 7' within the cylinder 1, based on the type and temperature of the target fluid. It follows that.

In each of the above embodiments, only one check valve 1 is disposed on the suction side, but even if it is disposed on the discharge side, for example, in the discharge passage 14,
The function of the micro space as a fluid passage and a check valve can be similarly expected.

As described above, the present invention makes the plunger that reciprocates within the cylinder a solid block, and reduces the minute distance between the outer peripheral surface of the plunger and the inner peripheral surface of the cylinder necessary for reciprocating the plunger. It is used for the fluid passage and functions as a substantial check valve, so that the check valve that requires a valve spring is only on the suction side or the discharge side, and the plunger has a diameter of 0.4~ Since the process of drilling a small hole of 0.6 mm, which is highly difficult to process, as in the conventional example, is not necessary, the structure of the plunger part can be significantly simplified and the manufacturing of this part can be made very easy. It is expected that the instability factors that affect pump performance can be significantly reduced, and that electromagnetic pumps with good pump performance can be supplied at low cost.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view showing an embodiment of the present invention, Fig. 2 is a sectional view taken from the - line in Fig. 1,
FIG. 3 is a sectional view showing the main parts of another embodiment. 1...Cylinder, 2...Cylinder pipe, 3,
4...Cylinder plug, 5...Protrusion, 5'...
Through hole, 7, 7'... Plunger, 8, 9... Holding spring, 12... Suction port, 15... Discharge port, 16...
...Check valve, 17...Valve seat, 18...Valve spring, 19
... Electromagnetic coil, 21 ... Yoke, 24 ... Mounting protrusion, 27 ... Pump mounting seat.

Claims (1)

[Claims for Utility Model Registration] (1) A plunger that can reciprocate in the direction of the cylinder center line is installed inside a cylinder whose outer periphery is surrounded by an electromagnetic coil held by a yoke, and the plunger is attached to both ends of the cylinder. An electromagnetic pump containing holding springs for individually lightly pressing the cylinder, and a cylinder made of a ferromagnetic material that is fitted and fixed to the discharge end side of a cylinder pipe made of a non-magnetic material that constitutes the cylinder. From the plug, a protrusion that is thinner than the inner diameter of the cylinder provided in the plug and has a through hole at its base is deeply inserted into the pipe, and the plunger is inserted near the tip of the protrusion to insert each of the above. The plunger is elastically held by a retaining spring, and the plunger is an internal solid block, and the minute distance required to reciprocate the plunger between the outer peripheral surface of the plunger and the inner peripheral surface of the cylinder is as follows: An electromagnetic pump characterized in that the check valve is a fluid passage having substantially the function of a check valve and is provided with a valve spring only on either the suction side or the discharge side of the cylinder. (2) The electromagnetic pump described in claim 1 of the utility model registration claim, wherein the plunger of the lump is spherical. (3) The electromagnetic pump as set forth in claim 1 of the utility model registration claim, characterized in that the lumpy plunger has a short cylindrical shape.