JP2001027181A - Diaphragm pump, and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm pump to reduce the driving force and to obtain the sufficiently effective working length. SOLUTION: In this diaphragm pump, large and small two diaphragms 14, 15 are arranged in a casing 12 opposite to each other to form a pump chamber 16 by these diaphragms 14, 15 and the casing 12, an inlet 18 and an outlet 19 of the fluid are provided in the casing 12, the diaphragms 14, 15 are coupled by a rod 20 formed of a permanent magnet, and an electromagnetic coil 21 is arranged outside this rod 20. The volume of the pump chamber 16 is increased/decreased to implement the pumping effect by alternately displacing two diaphragms 14, 15 in the same direction by the same quantity. The drive force can be substantially same as that required for driving a small diaphragm having an area equal to the difference between the areas of two diaphragms 14, 15. Since a large diaphragm is used, a sufficiently effective working length can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm pump, and more particularly to a diaphragm pump that can be used as a fuel injection pump for an internal combustion engine and a method of driving the same.

[0002]

2. Description of the Related Art At present, Wesco pumps are mainly used as fuel injection pumps for automobiles and motorcycles. In this Wesco pump, a rotor having a large number of blades is rotated in a casing. The fuel is pressed against the inner peripheral wall of the casing by the centrifugal force received from the rotating blade pieces, moves in the circumferential direction by the rotation of the rotor, and proceeds to the outlet. However, this circumferential movement is not linear, but proceeds while circulating around the blade piece in the radial direction of the rotor, so that the fuel spirals in the casing and is transported to the discharge port. Will be done. The pump casing is stopped, and fuel flows spirally on the inner wall surface of the casing while being pressed against the inner peripheral wall of the casing by strong centrifugal force, so that the pump efficiency is poor due to friction with the inner peripheral wall. There is a feature that becomes.

On the other hand, 0.3 k is mainly used for carburetors.
A g / cm ² low-pressure diaphragm pump is used. Since the diaphragm pump is a completely sealed volume type, the pump efficiency is higher than that of the Wesco type. As a positive displacement pump, a plunger pump is typical. However, a diaphragm pump has a smaller weight of a movable part and can be easily moved at high speed as compared with a plunger pump. Since the structure is relatively simple, it can be manufactured at low cost. Since there are no sliding parts, there is no wear, high durability, and low noise. High pressure delivery is also possible. Therefore, it can be considered to be used for fuel injection.

[0004]

However, when used as a high-pressure (about 2.5 kg / cm ² ) high flow rate pump for fuel injection, it is necessary to increase the area of the diaphragm. Therefore, large power is required for driving, miniaturization,
It was difficult to achieve low power consumption. In particular, in the case of a motorcycle, EFI is rapidly progressing, but in a small displacement vehicle, a load for driving a diaphragm pump is increased, which is a problem that cannot be ignored.

[0005] On the other hand, when the diameter of the diaphragm is reduced, the driving power is reduced, but the effective operating length cannot be secured, and a problem arises in that a sufficient pump discharge amount cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a diaphragm pump capable of reducing the driving force and obtaining a sufficient effective operating length, and a method of driving the diaphragm pump. I have.

[0007]

In order to achieve the above object, a diaphragm pump according to the present invention comprises a casing in which two large and small diaphragms are opposed to each other, and a pump chamber is formed by the diaphragm and the casing. The casing is provided with an inlet and an outlet for the fluid that communicates with the pump chamber, and a driving means for simultaneously providing the diaphragm with a displacement in the same direction is provided, so that the driving means can apply an alternating displacement to each of the diaphragms. It is characterized by:

The driving means may have a rod connecting the centers of the opposed diaphragms, or the driving means may have an electromagnetic coil for moving the rod back and forth in the axial direction. The drive means may have a motor for reciprocating the rod in the axial direction thereof.

Further, a method of driving a diaphragm pump according to the present invention is characterized in that, in any of the above-described diaphragm pumps, the driving means applies a driving force having the same frequency as the resonance frequency of the movable portion to the diaphragm. .

Alternatively, in any of the above diaphragm pumps, a check valve is provided at an inlet and an outlet, and the driving means applies a driving force of a high frequency to the diaphragm as far as the check valve can follow. It is characterized by.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a diaphragm pump 1 according to the present invention.
It is sectional drawing which shows an Example.

Referring to FIG.
It is divided into two, three and two. Central casing 1
Diaphragms 14 and 15 are attached to both sides of 2, and casings 11 and 13 are flange-connected from both sides. A portion surrounded by the central casing 12 and the diaphragms 14 and 15 on both sides thereof becomes a pump chamber 16. The diameter of the diaphragm 14 is larger than the diameter of the diaphragm 15.

The central casing 12 has an inlet 18 at the bottom and an outlet 19 at the top. A check valve such as a ball valve (not shown) is provided at the end of each of the inlet and outlet pipes. It is provided to allow a fluid such as fuel to flow from an inlet indicated by an arrow to an outlet.

The center of the two diaphragms 14, 15 is
They are integrally connected by a rod 20 made of a permanent magnet, and a cylindrical electromagnetic coil 21 is provided around the rod 20.
An AC voltage is applied to the electromagnetic coil 21 from a power source (not shown). The rod 20 and the electromagnetic coil 21 constitute driving means.

Further, the casings 11 and 13 on both sides are provided with elastic means 23 and 24 composed of coil springs, and urge the diaphragms 14 and 15 toward the pump chamber 16 respectively.

The operation of the diaphragm pump according to the present invention will be described with reference to FIG. When a current in one direction flows through the electromagnetic coil 21, the electromagnetic coil is excited to become an electromagnet, and the rod 20 made of a permanent magnet receives the magnetic force of the electromagnetic coil, for example, a leftward force in FIG. To the left, and to the position shown by the two-dot chain line 20 '. As a result, the diaphragm 14 becomes a two-dot chain line 14 '.
The diaphragm 15 also changes to the two-dot chain line 15 ′, and the forces are balanced. At this time, the displacement amounts (effective operating lengths) L1 and L2 of both diaphragms are equal.

Here, the diaphragm 14 is connected to a pump chamber 16.
Move in the direction in which the volume of the pump chamber 16 increases, and the diaphragm 15 moves in the direction in which the volume of the pump chamber 16 decreases. And
Assuming that the volume increase due to the diaphragm 14 is V and the volume decrease due to the diaphragm 15 is v, the volume increase V of the large-diameter diaphragm 14 is larger than the volume decrease v of the small-diameter diaphragm 15. Room 16
Means that the volume has increased by (V−v).
Therefore, fluid is taken in from the inlet 18 by this volume increase.

Next, when the power supply to the electromagnetic coil 21 is stopped, the rod 21 returns to the original position, and the diaphragm 1
4 and 15 return to the positions indicated by the solid lines. At this time, pump room 1
Since the volume of 6 also returns to its original state, the fuel (Vv) of the previously increased amount is discharged from the outlet 19 to the outside of the pump.

Next, when the direction of the current flowing through the electromagnetic coil 21 is reversed, the rod 20 moves in the opposite direction, that is, to the right in the drawing. Then, the diaphragm 14 is moved to a position 14 "indicated by a dotted line, and the diaphragm 15 is moved to a position 15" indicated by a dotted line.
Move to balance.

The volume of the pump chamber 16 is reduced because the large diaphragm 14 moves from the solid line to the dotted line. Since the small diaphragm 15 also moves from the solid line to the dotted line, the volume v increases and decreases by the difference (V−v). Accordingly, the same fluid as the reduced volume will be continuously pushed out from the outlet 19.

Since alternating current is applied to the electromagnetic coil 21, an alternating force is applied to the rod 20,
The diaphragms 14 and 15 also make one reciprocation between the two-dot chain line and the dotted line each time the reciprocation is performed, and 2 (Vv) fuel is sucked from the inlet 18 and discharged from the outlet 19 each time. .

Here, the energy required for deformation of the diaphragms 14 and 15 will be considered. First, the energy W required for deformation of the diaphragm 14 when moving from the solid line to the alternate long and two short dashes line is a positive load on the electromagnetic coil 21 because the energy W is applied against the resistance of the elastic means 23. The energy w required for deformation of the elastic member 15 is a negative load because the stretching force of the elastic means 24 is used, and the work actually performed by the electromagnetic coil and the rod is the difference between these, that is, (W−w). Just get better.

When moving from the solid line to the dotted line, the direction of work performed by the electromagnetic coil 21 and the rod 20 is opposite to the direction of the current flowing first, but the amount of work is the same as the previous time. .

Then, the W, w, or volume change
The amounts of conversion V and v are almost proportional to the pressure receiving area of the diaphragm.
You can think. The pressure receiving area of the diaphragm is
Proportional to the square of the effective diameter of the
The effective diameter of one diaphragm 14 is 10φ, and the smaller one is
When the effective diameter of the diaphragm 15 is 8φ, 10 ²
-8²= 6²And the diaphragm pump of FIG.
Same as a pump with an effective diaphragm diameter of 6φ as a body
Become.

That is, in the diaphragm pump of the present invention, since the sizes of the opposed diaphragms are different, the difference between these areas (the diameter of 6φ in the above example).
It can be operated with almost the same power as a diaphragm pump having. On the other hand, the amount of displacement (effective operating length) of the diaphragm can be given in the same manner as in the case of a large-diameter diaphragm, so that V-v can be set freely, the driving force is small, and sufficient discharge pressure and discharge A diaphragm pump with a large volume can be obtained.

FIG. 3 is a view showing a second embodiment of the present invention. Since most of them are common to the embodiment of FIG. 1, the description will focus on the differences. In this embodiment, the left and right diaphragms 1
The rods 4 and 15 are connected by a rod 25. In contrast to the rod of FIG. 1 which is a permanent magnet, this embodiment uses an unmagnetized rod. One end of the rod 25 is rotatably connected to one end of a connecting arm 26, and the other end of the connecting arm 26 is rotatably connected to a position off the center of a disk 28 rotated by a motor.

When the motor rotates and the disk 28 rotates in the direction of the arrow, the rod 25 reciprocates in its axial direction and is pumped. The displacement amount, the discharge amount, the driving energy, and the like are the same as those in the embodiment of FIG.

In the embodiment shown in FIGS. 1 and 2, a periodic and alternating force is applied to the rods 20 and 25 for driving the diaphragms 14 and 15, and this frequency is set to the resonance frequency of the vibrating mechanical system. If they are the same, the amount of inertia energy can be ignored, so that the pump can be driven with the smallest power.

FIG. 4 is a diagram showing a pressure change of the diaphragm pump of FIG. The vertical axis is the pressure (discharge pressure) of the fluid at the pump outlet 19, and the horizontal axis is time.
(A) is a case where the drive frequency of the electricity applied to the electromagnetic coil 21 is low. The operation of the pump is intermittent, and fuel is intermittently discharged from the pump outlet. As the discharge pressure, peaks similar to the shape of one side of the sine curve appear apart. That is, in this state, the pressure fluctuation of the fuel pulsates greatly.

FIG. 4B shows a case where the driving frequency is increased. Since the same peaks as in (a) appear at short time intervals, the pressure is as if the low peaks were continuously connected, and the pulsation was small.

From the above, it can be seen that the higher the driving frequency, the smaller the pulsation. That is, it is preferable to apply high-frequency vibrations as long as the mechanical system can follow. On the other hand, the diaphragm has good followability to high-frequency vibration, and
The followability of the check valve attached to the outlet 8 and the outlet 19 is more problematic. Therefore, pulsation can be reduced by applying high-frequency vibration as much as the check valve can follow. further,
If possible, high frequency vibrations near the check limit of the check valve
Most preferably, the resonance frequency of the mechanical system is set.

In the above embodiment, various modifications are possible. For example, although the casing is divided into 11, 12, and 13, the casings 11 and 13 on both sides only need to be able to hold the elastic means 23 and 24, and thus do not need to have a closed structure. Therefore, as the casing, the center 1
There can be only two.

In the embodiment, the rod of the driving means is also disposed in the pump chamber between the two diaphragms.
Various configurations such as a configuration in which the outsides of two diaphragms are connected to each other using a U-shaped frame can be adopted.

[0034]

According to the present invention as described above,
Two large and small diaphragms are arranged in the casing so as to face each other, a pump chamber is formed by these diaphragms and the casing, and an inlet and an outlet for a fluid communicating with the pump chamber are provided in the casing. Is provided at the same time, so that the driving means can add an alternating displacement to each diaphragm,
It can be driven with almost the same power as a small-diameter diaphragm pump having the area of the area difference between the large and small diaphragms, and can provide a displacement amount to the large-diameter diaphragm. As a result, a diaphragm pump having a small driving force, high efficiency, and a high discharge amount can be obtained.

If the diaphragm pump is driven at the same frequency as the resonance frequency of the movable part, it can be operated with the smallest driving force. In the above-described diaphragm pump, check valves are provided at the inlet and the outlet, and the driving means applies a high-frequency driving force to the diaphragm as far as the check valve can follow. Pulsation can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of a diaphragm pump according to the present invention.

FIG. 2 is a diagram illustrating the operation of the diaphragm pump of FIG.

FIG. 3 is a sectional view showing a configuration of another embodiment of the diaphragm pump.

FIG. 4 is a diagram showing a state of a discharge pressure of the diaphragm pump of the present invention.

[Explanation of symbols]

 11, 12, 13 Casing 14, 15 Diaphragm 16 Pump chamber 18 Inlet 19 Outlet 20, 25 Rod 21 Electromagnetic coil

Claims (6)

[Claims] 1. A large-sized and small-diameter diaphragm is opposed to a casing, a pump chamber is formed by the diaphragm and the casing, and an inlet and an outlet for a fluid communicating with the pump chamber are provided in the casing. A diaphragm pump comprising a driving means for simultaneously providing displacements in the same direction, wherein the driving means can apply an alternating displacement to each diaphragm. 2. The diaphragm pump according to claim 1, wherein said driving means has a rod connecting the centers of said opposed diaphragms. 3. The diaphragm pump according to claim 2, wherein said driving means has an electromagnetic coil for moving said rod forward and backward in its axial direction. 4. The diaphragm pump according to claim 2, wherein said driving means has a motor for reciprocating the rod in an axial direction thereof. 5. The diaphragm pump driving method according to claim 1, wherein said driving means applies a driving force having the same frequency as a resonance frequency of a movable portion to said diaphragm. 6. The diaphragm pump according to claim 1, wherein a check valve is provided at an inlet and an outlet, and the driving means generates a driving force having a high frequency as far as the check valve can follow. A method for driving a diaphragm pump, characterized in that the method is applied to a diaphragm.