JPH07259741A - Diaphragm pump - Google Patents

Abstract

PURPOSE:To dissipate beforehand danger of a diaphragm breaking when a feed pressure is lowered. CONSTITUTION:A pump body 1 is provided with diaphragm 5 which is located between a chamber 8 for fluid to be fed with a pressure and a working oil chamber 9. When a plunger 11 is raised through rotation of a cam 16, a reset port 12 is first closed, working oil in the working oil chamber 9 is pressurized at a following raising stroke, and fluid to be fed with a pressure in the chamber 8 is indirectly pressurized through the diaphragm 5. The fluid to be fed with a pressure pressurized up to a feed pressure with the aid of a low pressure feed pump 22 is sucked in the chamber 8 from a tank 21. When a feed pressure is abnormally lowered, the abnormal reduction is transmitted to a forced feed stop valve 25 through a sensing pipe 37 to move a diaphragm 27 to the left. A poppet valve 33 is opened and the working oil is released in a cam chamber 19 through a drain pipe 35 after the passage of it through a relief pipe 34. This constitution prevents the occurrence of deformation of the diaphragm 5 and the occurrence of breakage thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm pump for indirectly pressurizing a pressurized fluid such as a fuel of an internal combustion engine through a diaphragm with pressurized hydraulic oil.

[0002]

2. Description of the Related Art Instead of directly pressurizing a fluid to be pressurized such as fuel, another hydraulic fluid is pressurized by a plunger pump or the like that generates high pressure, and the pressure of the hydraulic fluid is transmitted to the fluid to be pressurized via a diaphragm. , A diaphragm pump that indirectly pressurizes the fluid to be pressurized, that is, pressurizes the fluid to a high pressure without contacting the high pressure pump, has been studied. The diaphragm pump is advantageous when the fluid to be pumped has the property of dissolving the lubricating oil of the high-pressure pump, and when it is directly pressurized by the high-pressure pump, problems such as lubricity occur.
For the hydraulic oil, it is possible to use one that has optimal properties in terms of viscosity and lubricity for a high pressure pump such as a plunger pump, and since the hydraulic oil and the fluid to be pressurized are completely separated by the diaphragm, This is because there is no possibility that the fluid to be pressure-fed mixes with the hydraulic oil or the reverse of that.

In this type of diaphragm pump,
Prior to pressurizing the fluid to be pressurized to a high pressure, the fluid to be pressurized, which has been pressurized to a relatively low feed pressure by another low-pressure feed pump, is sucked, but in the suction stroke, it is deformed in the pressure stroke. It is necessary for the diaphragm to return to its initial position by returning to its original shape by being pressed by the restoring force of the inherent elasticity and the feed pressure.

[0004]

However, when the diaphragm pump is used at a very low temperature, the viscosity of the hydraulic oil increases and the diaphragm returns slowly, but at that time, the low pressure feed occurs. If the pump malfunctions or an accident occurs such that there is no pressurized fluid in the pressurized fluid tank, and the feed pressure, which is the discharge pressure of the low-pressure feed pump, drops abnormally, the diaphragm of the diaphragm pump is completely removed during the suction stroke. It becomes impossible to return to the original shape, and at least part of the deformation in the pressurizing stroke remains, so if it is deformed again in the next pressurizing stroke, the deformation will be superimposed and excessive displacement will occur. This can lead to problems with diaphragm damage.

In order to eliminate the above-mentioned concerns in the conventional diaphragm pump, the present invention substantially suspends the function of the diaphragm pump and stops the discharge of the fluid to be pressurized when the feed pressure is abnormally lowered. By doing so, it is an object of the present invention to provide a means for preventing damage to the diaphragm and ensuring safety.

[0006]

Means for Solving the Problems The present invention is, as a means for solving the above problems, at least a pressurized fluid chamber for sucking and pressurizing a fluid to be pressurized and discharging the fluid to the outside, and suctioning another hydraulic oil. A hydraulic oil chamber that pressurizes, a diaphragm that divides between the pressurized fluid chamber and the hydraulic oil chamber to transmit the pressure of the hydraulic oil to the fluid to be pressurized, and that is sucked into the fluid chamber to be pressurized. A diaphragm pump provided with means for discharging high-pressure hydraulic oil in the hydraulic oil chamber to a space on the low-pressure side when the feed pressure of the fluid to be pumped falls below a predetermined value.

[0007]

In the diaphragm pump of the present invention, when the feed pressure of the pressurized fluid to be sucked into the pressurized fluid chamber drops below a predetermined value, the high pressure hydraulic oil in the hydraulic fluid chamber is discharged to the space on the low pressure side. Since the discharging means is additionally provided, in such an abnormal state, the pressure rise in the hydraulic oil chamber is prevented, the diaphragm is not driven, and the fluid pumping function of the diaphragm pump is stopped. Therefore, it is possible to avoid a situation in which the diaphragm is abnormally deformed and damaged due to a decrease in the feed pressure acting on the pressurized fluid chamber.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of a diaphragm pump according to the present invention. A diaphragm pump body 1 comprises an upper housing 2 at an upper portion and a lower housing 3 integrally attached to a lower portion thereof. ing. Inside thereof, a retaining nut 4 is screwed from below onto a threaded portion on the outer periphery of a projecting portion 2a formed so as to hang down from the upper housing 2, whereby a diaphragm 5 is formed.
A lower stopper 6 that is a perforated circular plate that supports it from below and a funnel-shaped retainer 7 are integrally attached to the upper housing 2. The diaphragm 5 divides a pressurized fluid chamber 8 that is a space formed on the lower surface of the depending protrusion 2a of the upper housing 2 and a hydraulic oil chamber 9 that is a space formed on the upper surface of the retainer 7 into upper and lower parts. .

A cylinder 10 is formed in the center of the retainer 7 so as to extend vertically therethrough, and a plunger 11 is slidably inserted therein. At least one reset port 12 that opens when the plunger 11 descends near the bottom dead center is bored in the wall surface of the cylinder 10 in the radial direction, so that the reset port 12 is provided inside the lower housing 3 and outside the retainer 7. The formed low pressure chamber 13 and the above-mentioned hydraulic oil chamber 9 communicate with each other. The plunger 11 is constantly urged downward by a compression spring 14 mounted between the retainer 7 and the plunger 11. The plunger 11 is in sliding contact with the eccentric cam 16 by an integrated tappet 15, and when the cam 16 rotates. By the balance with the urging force of the spring 14, it reciprocates in the vertical direction. Reference numeral 17 schematically indicated by a broken line is a drive shaft integrated with the cam 16.

A cam chamber 19 which is continuously provided as a part of the lower housing 3 and accommodates the cam 16 accommodates at least one opening 15a formed in the tappet 15 and the spring 14. It constantly communicates with the low pressure chamber 13 described above through the space 18 and the like. A reset port 12, a low pressure chamber 13, a space 18 and a cam chamber 1 thereby forming one continuous low pressure side space behind the plunger 11.
9 is filled with the same hydraulic oil as that in the hydraulic oil chamber 9.

The inlet 20 of the diaphragm pump main body 1 attached to the upper housing 2 sucks up the pressurized fluid such as the fuel of the internal combustion engine from the tank 21 which stores the fluid to be pressurized to a predetermined relatively low pressure. It is connected to a low-pressure feed pump 22 that is pressurized, for example, an electric type, and communicates with the above-mentioned pressurized fluid chamber 8 inside the pump body 1 via a solenoid valve 23 for metering. The pressurized fluid in the pressurized fluid chamber 8 is pressurized to a high pressure by the pressurized hydraulic oil in the hydraulic oil chamber 9 via the diaphragm 5, but the pressurized pressurized fluid is delivered to the outside. Therefore, a discharge valve 24 as a check valve, which is composed of a ball and a compression spring for urging the ball toward the valve seat, is provided so as to be connected to the pressurized fluid chamber 8. The solenoid valve 21 for metering is an electronic control unit (E
CU) controls the opening and closing.

The main body 1 of the diaphragm pump and the basic parts relating to the feeding of the fluid to be pumped in the illustrated embodiment have the above-mentioned structure, but the structure and operation of these parts are conventional. However, these constituent parts are not particularly new in the present invention.

Corresponding to the features of the present invention, in the first embodiment, the pump main body 1 is provided with a pressure feed stop valve 25. The housing 26 of the pressure feed stop valve 25 is composed of a housing half portion 26a on the left side and a housing half portion 26b on the right side in FIG. 1, both of which are bowl-shaped, and a sensing diaphragm 27 is sandwiched therebetween, and caulking is performed. It is integrated by the method such as. Therefore, the internal space of the housing 26 of the pressure feed stop valve 25 is partitioned by the diaphragm 27 so as to be in an airtight state so as to be two parts, that is, the first chamber 25a and the second chamber 25b that are independent of each other.

In the pressure feed stop valve 25 of the first embodiment,
A pair of plates 28 and 29 sandwiching the central portion of the diaphragm 27 from both sides are formed into a cylindrical valve body 3 by bolts 30.
It is attached to 1. The valve body 31 is hermetically fitted in a cylindrical hole formed in the right housing half portion 26b,
It can slide back and forth in the axial direction. Disc 3
The conical tip of 1 can close the opening 32 of the valve seat, which is the inlet of the valve chamber 25c, and thereby the poppet valve 3
Make up three.

The opening 32 of the valve seat of the poppet valve 33 is connected to the hydraulic oil chamber 9 by the relief pipe 34, and the outlet 25d, which is the other opening of the valve chamber 25c, is drained by the drain pipe 35. 19, or the low-pressure chamber 13 that is in constant communication with it, or the space 18 in some cases, is connected to the low-pressure side behind when viewed from the hydraulic oil chamber 9 side where the plunger 11 pressurizes the hydraulic oil.

The sensing diaphragm 27 is biased to the left in FIG. 1 by the compression spring 36,
The force acts in the direction in which the valve body 31 opens the opening 32 of the valve seat. In addition, at the opening 32 of the valve seat of the poppet valve 33, the pressure of the hydraulic oil chamber 9 acts on the surface of the tip of the valve body 31 which closes the valve seat 31, which also causes the valve body 31 to move to the left. Press to. However, the first chamber 25 a of the pressure feed stop valve 25 is connected to the inlet 2 by the sensing pipe 37.
Since the feed pressure, which is the discharge pressure of the low pressure feed pump 22, is introduced, the feed pressure acts on the left side of the diaphragm 27 to move the valve body 31, normally the spring 36 and the valve seat. Since the pressure is pushed to the right with a force stronger than the resultant force due to the pressure of the hydraulic oil acting on the opening 32, the feed pressure drops below a predetermined value due to a failure of the low-pressure feed pump 22 or exhaustion of the tank 21. The poppet valve 33 does not open unless the state is reached.

When the diaphragm pump of the first embodiment provided with the pressure feed stop valve 25 as described above is put into an operating state, when the cam 16 is rotated by the drive shaft 17 and pushes up the plunger 11, the plunger 11 firstly moves. Since the reset port 12 opening on the wall surface of the cylinder 10 is closed, the pressure of the working oil in the working oil chamber 9 rises in the ascending stroke after the closing, and the pressurized fluid delivery chamber 8 is indirectly passed through the diaphragm 5. Press the fluid to be pumped inside. At this time, if the metering solenoid valve 23 is closed by a control signal output from an ECU (not shown), the pressurized fluid pressurized in the chamber 8 pushes the discharge valve 24 to open the internal combustion engine. The fuel is discharged toward an external target location (not shown) such as a fuel injection valve provided in the combustion chamber.

As described above, the combined force of several forces acting on the diaphragm 27 of the pressure feed stop valve 25 from the left and right is shown in FIG.
, The area of the opening 32 of the valve seat, the spring constant of the spring 36, etc. are appropriately set with respect to the normal discharge pressure of the low-pressure feed pump 22, and the magnitude of the left and right forces of the diaphragm 27 is set. Therefore, in the normal operation state of the diaphragm pump, the poppet valve 33 is kept closed, and in the rising stroke of the plunger 11 after closing the reset port 12, the hydraulic oil chamber 9 is changed to the cam chamber. Since the hydraulic fluid in the hydraulic fluid chamber 9 is pressurized by the plunger 11, the pressurized fluid in the chamber 8 is indirectly pressurized via the diaphragm 5 because it is not communicated with the low pressure side such as 19. Is discharged from the discharge valve 24 to the outside.

Needless to say, in the downward stroke of the plunger 11, the hydraulic oil pressure in the hydraulic oil chamber 9 decreases, and the diaphragm 5 moves downward due to the restoring force of the elasticity of the diaphragm 5 itself and the discharge pressure of the low pressure feed pump 22. It deforms to increase the volume of the pressurized fluid chamber 8 and receives the pressurized fluid pressurized from the low pressure feed pump 22 to a predetermined feed pressure. This is pressurized in the pressurized fluid chamber 8 in the next ascending stroke of the plunger 11. in this way,
By repeating the upward stroke and the downward stroke of the plunger 11, the pressurized fluid in the tank 21 is pressurized to a predetermined high pressure in the pressurized fluid chamber 8 and is discharged from the discharge valve 24.

If, for example, the low-pressure feed pump 22 is out of order or the pressurized fluid in the tank 21 is depleted, the feed pressure is reduced, and the pressure of the pressurized fluid to be sucked into the pressurized fluid chamber 8 in the descending stroke of the plunger 11. Is decreased to an abnormal value, in the conventional diaphragm pump, the diaphragm 5 remains deformed upward during the ascending stroke of the plunger 11, and does not sufficiently recover downward even during the descending stroke. When the high-pressure hydraulic oil is sent into the hydraulic oil chamber 9 again in the ascending stroke and the hydraulic pressure becomes high, the hydraulic oil chamber 9 is further deformed upward, which may eventually cause the diaphragm 5 to be damaged.

However, in the first embodiment, since the pressure feed stop valve 25 is attached to the body 1 of the diaphragm pump, the feed pressure of the low pressure feed pump 22 acting in the fluid feed chamber 8 is not more than a predetermined value. Then, at the same time, the first chamber 25a of the pressure feed stop valve 25 also has the same low pressure through the sensing pipe 37, so the force pressing the diaphragm 27 to the right in FIG. 1 becomes smaller. Therefore, the urging force of the spring 36 that constantly presses the diaphragm 27 to the left than that force, and the hydraulic oil pressure of the hydraulic oil chamber 9 that acts on the valve body 31 at the opening 32 of the valve seat of the poppet valve 33. The total force of
The diaphragm 27 and the valve body 31 are pushed leftward to open the poppet valve 33.

As a result, the hydraulic oil pumped into the hydraulic oil chamber 9 in the upward stroke of the plunger 11 is discharged to the low pressure side space such as the cam chamber 19 through the relief pipe 34, the poppet valve 33, and the drain pipe 35. Therefore, since the pressure in the hydraulic oil chamber 9 is not increased, the effective compression action of the pump body 1 on the fluid to be pressurized is stopped, and the diaphragm 5
Can be prevented from being damaged.

A second embodiment of the diaphragm pump of the present invention is shown in FIG. Also in this case, the main body 1 of the diaphragm pump, the tank 21, the low-pressure feed pump 22 and the like have the same configuration as that of the first embodiment shown in FIG. Therefore, detailed description of the structure of the pump body 1 and the like will be omitted. In the first embodiment, the diaphragm 2 of the pressure feed stop valve 25 is activated when the pressure in the fluid feed chamber 8 drops abnormally.
7 has a mechanical structure in which the hydraulic oil pressure in the hydraulic oil chamber 9 is lowered by detecting this and opening the poppet valve 33, but in the second embodiment, the hydraulic fluid chamber 8 to be pressurized is supplied. Although the pressure or the feed pressure of the low-pressure feed pump 22 is also taken out from the inlet 20 by the sensing pipe 37, it is detected by the pressure sensor 38 and an electric pressure signal is output.

The pressure sensor 38 is connected to the ECU 39,
When the ECU 39 determines that the pressure of the pressurized fluid chamber 8 has abnormally dropped to a predetermined value or less by the pressure signal, the normally closed solenoid valve 40 provided between the relief pipe 34 and the drain pipe 35 is opened. It outputs a control signal to cause it. Therefore, the solenoid valve 40 operates in the same manner as the poppet valve 33 of the first embodiment, and when the feed pressure shows an abnormal decrease, the hydraulic oil pressure in the hydraulic oil chamber 9 is released to the cam chamber 19, and the hydraulic oil is released. The rise of the pressure in the chamber 9 is stopped to prevent the diaphragm 5 from being deformed upward, and the diaphragm 5 is protected from being damaged.

[0025]

According to the present invention, it is possible to prevent the diaphragm from being damaged when the feed pressure is lowered in the conventional diaphragm pump, and to prevent more serious damage from occurring. .

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

 1 ... Main body of diaphragm pump 5 ... Diaphragm 6 ... Lower stopper 7 ... Retainer 8 ... Pressurized fluid chamber 9 ... Hydraulic fluid chamber 10 ... Cylinder 11 ... Plunger 12 ... Reset port 13 ... Low pressure chamber 16 ... Cam 19 ... Cam chamber 20 ... Inlet 21 ... Tank for pressurized fluid 22 ... Low-pressure feed pump 23 ... Solenoid valve for metering 24 ... Discharge valve 25 ... Stop feeding valve 27 ... Sensing diaphragm 31 ... Valve body 32 ... Opening of valve seat 33 ... Poppet valve 34 ... Relief pipe 35 ... Drain pipe 36 ... Spring 37 ... Sensing pipe 38 ... Pressure sensor 40 ... Normally closed solenoid valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhide Watanabe 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Prefecture Japan Auto Parts Research Institute, Inc.

Claims (4)

[Claims] 1. At least a pressurized fluid chamber for sucking and pressurizing a pressurized fluid and discharging the fluid to the outside, a hydraulic oil chamber for sucking and pressurizing another hydraulic oil, and a space between the pressurized fluid chamber and the hydraulic oil chamber. The hydraulic oil chamber is provided with a diaphragm that divides and transmits the pressure of the hydraulic oil to the pressurized fluid, and when the feed pressure of the pressurized fluid sucked into the pressurized fluid chamber drops below a predetermined value. A diaphragm pump provided with a means for discharging the high-pressure hydraulic oil to the space on the low-pressure side. 2. A cam behind the plunger in which the working oil in the working oil chamber is sucked and pressurized by a plunger driven by a cam to reciprocate and the space on the low pressure side accommodates the cam. Claim 1 which is a room
The diaphragm pump described. 3. A diaphragm, wherein the means for discharging high-pressure hydraulic oil in the hydraulic oil chamber to a space on the low-pressure side is operated by a feed pressure of a fluid to be pressurized to the fluid chamber to be pressurized, which is different from the diaphragm. The diaphragm pump according to claim 1, comprising a pressure feed stop valve including the. 4. A pressure sensor for discharging a high pressure hydraulic oil in the hydraulic oil chamber to a space on the low pressure side, the pressure sensor detecting a feed pressure of the pressurized fluid to the pressurized fluid chamber and outputting a pressure signal. 2. The diaphragm pump according to claim 1, further comprising: a control device that processes a pressure signal to determine the activation timing of the means; and a valve that operates according to a control signal output by the control device.