JP2002070747A - Diaphragm pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm pump capable of feeding a liquid by pressurizing it to a determined pressure by an amount requested by a customer. SOLUTION: The diaphragm pump 4 partitioning a pumping chamber 2 and a working chamber 3 in a housing 1 is operated by the pressure plunger 7 of a fluid cylinder 5. The fluid cylinder 5 comprising a pressure spring 10 urging the pressure plunger 7 forwardly, a return piston 11 not pressurizing the pressure plunger 7 when pressure is applied from outside but returning the pressure plunger 7 by a return action produced when pressuring is relieved, a return spring 12 urging the return piston 11 backwardly, receiving compression and not applying return force on the pressure plunger 7 when pressure is applied to the return piston 11 from outside and an eccentric cam 13 operating to pressurize the return piston 11 and retracting action by releasing the pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm pump suitable for use in, for example, a fuel injection device of an internal combustion engine.

[0002]

2. Description of the Related Art There are various types of pumps for supplying fuel to an internal combustion engine. A plunger reciprocating pump is often used as a pump for increasing the fuel pressure to a relatively high pressure of 2 MPa or more. In this case, since the pressurized fluid is low-viscosity fuel, the gap between the plunger and the cylinder must be reduced to prevent leakage. Therefore, the contact surface between the plunger and the cylinder requires high dimensional accuracy and high smoothness. As described above, the plunger reciprocating pump requires a high processing accuracy, and thus has a problem that the processing cost is increased.

Therefore, a diaphragm pump in which a reciprocating pump and a pressurized fluid are separated by a diaphragm, such as Japanese Patent Publication No. 38-16177, has been proposed. In this diaphragm pump, the working accuracy of the plunger and the cylinder can be reduced by using a highly viscous working oil as the working fluid of the reciprocating pump. Further, the working oil has good lubricity, so that the life of the reciprocating pump can be extended. Further, in this case, since the hydraulic oil presses the diaphragm, the pressing force for pressing the diaphragm can be averaged on the diaphragm surface, and the breakage of the diaphragm can be prevented.

Further, as a cause of the diaphragm being damaged, there is a case where the pressure of the hydraulic oil is too high. In Japanese Patent Publication No. 38-16177, a relief valve is provided for the hydraulic oil to prevent the diaphragm from being damaged. are doing.

[0005]

However, in the diaphragm pump disclosed in Japanese Patent Publication No. 38-16177, the driving of the plunger is taken out from the shaft output, and the amount of hydraulic oil discharged from the relief valve is wasted. This means that the axis output has been consumed.

When fuel pressurized to a pressure of 2 MPa or more is supplied to the fuel injector through a fuel pipe, if the fuel pipe cracks and leaks, the fuel spreads in a mist and explodes. Because there is a danger of burning
The fuel pipe needs to have sufficient strength margin.

On the other hand, when the drive power source for the pump is taken out from the crankshaft of the internal combustion engine, the distance of the fuel pipe becomes long, and the fuel pipe having sufficient strength is drawn long, resulting in an increase in weight. become.

Particularly, in a two-stroke engine having no camshaft, if the pump is laid out near the injector and the piping length is optimized, the mechanism itself driven from the crankshaft becomes large, resulting in an increase in weight. Become.

Also, in an internal combustion engine of a recoil start without a battery, it is necessary to increase the fuel pressure in the fuel pipe within a small number of revolutions by the recoil. At the time of starting, if the fuel pipe volume is large, starting becomes difficult.

An object of the present invention is to provide a diaphragm pump capable of supplying a liquid by pressurizing the liquid to a predetermined pressure by an amount required by a supply destination.

Another object of the present invention is to provide a diaphragm pump that does not require a pressure regulator.

Another object of the present invention is to provide a diaphragm pump in which the pressure is not abnormally increased because the pressure plunger is advanced by the restoring force of the pressure spring.

Another object of the present invention is to provide a diaphragm pump capable of shortening the length of a supply pipe for a pressurized liquid.

Another object of the present invention is to provide a diaphragm pump which can automatically replenish even if hydraulic oil in a hydraulic oil chamber leaks from a sliding surface of a pressurizing plunger.

[0015]

According to the present invention, a diaphragm for separating a pump chamber and a hydraulic oil chamber in a housing is operated by a pressurizing plunger of a liquid cylinder connected to the hydraulic oil chamber, and the diaphragm is provided in the pump chamber. A diaphragm pump is provided which, when bent toward the side, feeds the liquid in the pump chamber by closing the check valve at the inlet of the pump chamber and opening the check valve at the outlet of the pump chamber.

In the diaphragm pump according to the present invention, the liquid cylinder has a pressure spring that urges the pressure plunger in the forward direction and does not press the pressure plunger when pressed from outside. A return piston that pulls back the pressure plunger in the return operation when the pressure is released, and a biasing force that returns the return piston with a restoring force greater than the restoring force of the pressurizing spring, and presses the return piston from outside. A return spring that is compressed when a pressure is applied and does not apply a return force to the pressure plunger, an operation of pressing the return piston in the direction of the pressure plunger, and an eccentric cam that releases the pressure and performs the evacuation operation. It is characterized by having.

In such a diaphragm pump, when the eccentric cam presses the return piston to compress the return spring and release the pressure plunger, the pressure plunger is pushed out by the restoring force of the pressure spring. The hydraulic oil is pressurized to push the diaphragm toward the pump chamber, thereby increasing the pressure of the liquid in the pump chamber, closing the check valve at the inlet of the pump chamber, and closing the check valve at the outlet of the pump chamber. Is opened, and the liquid in the pump chamber is supplied to the supply destination. Next, when the eccentric cam releases the pressing of the return piston and performs the retreat operation, the return spring having a larger restoring force than the restoring force of the pressurizing spring becomes free, and the returning piston is released from the restoring force of the returning spring. The pressure plunger is pushed out in the direction of the eccentric cam, and the pressure plunger is pulled back by the return operation of the return piston, and the pressure spring is compressed by the pull back of the pressure plunger.

For this reason, in this diaphragm pump, the pressurizing plunger is pushed out only by the restoring force of the pressurizing spring and presses the diaphragm toward the pump chamber via the hydraulic oil. Can be supplied by pressurizing it to a predetermined pressure by the amount required by.

Further, in this diaphragm pump, since the pressurized plunger moves to supplement only the liquid consumed by the supply destination, a pressure regulator for the pressurized liquid is not required, and the cost can be reduced.

Further, in this diaphragm pump, since the pressurizing plunger is advanced by the restoring force of the pressurizing spring, the pressure of the pressurized liquid does not rise abnormally, and a safety valve and a relief valve are not required.

In the diaphragm pump according to the present invention, the liquid cylinder is slidably inserted into a pressure spring for urging the pressure plunger in the forward direction, and into a cylindrical portion of the pressure plunger. A return rod that pulls back the pressure plunger by a return operation when the pressure is released when the pressure plunger is pressed from the outside without pressing the pressure plunger; A return rod pressing cam for periodically pressing in the direction of the jar and releasing the pressing to perform a retracting operation, and a return rod returning mechanism for retracting the return rod in the retracting direction when the return rod pressing cam performs the retracting operation. And characterized in that:

In such a diaphragm pump, when the return rod pushing cam pushes the return rod and pushes it into the pressurizing plunger to release the pressurizing plunger,
The pressurizing plunger is pushed out by the restoring force of the pressurizing spring, whereby the working oil is pressurized and the diaphragm is pushed out toward the pump chamber, whereby the pressure of the liquid in the pump chamber rises, and the inlet of the pump chamber is opened. Is closed and the check valve at the outlet of the pump chamber is opened, so that the liquid in the pump chamber is supplied to the supply destination. Next, when the return rod pushing cam releases the pressing of the return rod and performs the retreat operation, when the return rod return mechanism performs the return operation of pulling the return rod out of the pressurizing plunger, the return operation of the return rod causes an additional force. The pressure plunger is retracted, and the retraction of the pressure plunger compresses the pressure spring.

Therefore, the same effect as described above can be obtained in this diaphragm pump.

In this diaphragm pump, a strong return spring is not required.

In the diaphragm pump according to the present invention, the housing accommodating the diaphragm is formed separately from the liquid cylinder, and the hydraulic oil chamber of the liquid cylinder and the hydraulic oil chamber of the diaphragm are connected by a hydraulic oil supply pipe. It is characterized by having.

According to such a diaphragm pump,
The housing accommodating the diaphragm can be arranged close to the liquid supply destination, and the length of the pressurized liquid supply pipe from the housing accommodating the diaphragm to the liquid supply destination can be shortened. In addition, the piping connecting the housing containing the diaphragm and the liquid cylinder is hydraulic oil supply piping that supplies hydraulic oil that is difficult to burn, so even if this piping cracks and hydraulic oil blows out, explosive combustion may occur. There is no.

In the diaphragm pump according to the present invention, a hydraulic oil supply port for supplying hydraulic oil to the hydraulic oil chamber is provided through a check valve.

In this way, even if the hydraulic oil in the hydraulic oil chamber leaks from the sliding surface of the pressure plunger, it can be automatically replenished.

[0029]

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

The diaphragm pump comprises a housing 1
Diaphragm 4 for separating pump chamber 2 and hydraulic oil chamber 3 inside
Is operated by a pressure plunger 7 that slides in a cylinder body 6 of a liquid cylinder 5 connected to the hydraulic oil chamber 3, and when the diaphragm 4 is bent toward the pump chamber 2, the pressure in the pump chamber 2 is reduced. The liquid is sent out by closing the check valve 8 at the inlet of the pump chamber 2 and opening the check valve 9 at the outlet of the pump chamber 2. The liquid flowing in the pump chamber 2 is, for example, fuel for an internal combustion engine. As the working oil in the working oil chamber 3, for example, four-cycle engine oil is used.

In this case, the liquid cylinder 5 is provided with a pressure spring 10 which urges the pressure plunger 7 in the forward direction.
Does not press the pressure plunger 7 when it is fitted to the base end of the pressure plunger 7 and is pressed from the outside, but pulls back the pressure plunger 7 by the return operation when the pressure is released. The return plunger 11 and the return plunger 11 are urged in a return direction with a greater restoring force than the restoring force of the pressurizing spring 10, and are compressed when a pressing force is applied to the return piston 11 from the outside. A return spring 12 that does not apply a return force to the pressure piston 7 and an eccentric cam 13 that presses the return piston 11 in the direction of the pressure plunger 7 and releases the pressure to perform a retracting operation. The return piston 11 has a hollow structure.

In this example, the check valves 8 and 9 are vertically oriented and the valve holes 8a and 9b of the valve seats 8b and 9b are placed under the own weight of the ball valves 8a and 9a.
c, 9c. Pressurizing plunger 7
A piston ring 14 is supported on the outer periphery of the tip of
A seal is provided between the cylinder body 6 and the inner periphery thereof. The pressure spring 10 is fitted on the outer circumference of the pressure plunger 7, one end of which is supported by a spring receiver 15 protruding from the outer circumference of the pressure plunger 7, and the other end of which is mounted on the cylinder body 6.
Is supported by a spring receiver 16 protruding from the inner periphery of the spring. The return spring 12 is also fitted on the outer periphery of the pressure plunger 7, one end is supported by a spring receiver 16, and the other end is supported by the inner end of the return piston 11. Pressurizing plunger 7 slidably inserted into hollow return piston 11
A stopper 1 is provided at the base end for pulling out the pressure plunger 7 when the return piston 11 is pushed out by the return spring 12.
7 is fixed. The eccentric cam 13 is driven to rotate by a rotating shaft 18 such as a crankshaft of the internal combustion engine. In the cylinder body 6 corresponding to the hydraulic oil chamber 3, there is provided a hydraulic oil supply port 19 for replenishing when the hydraulic oil in the hydraulic oil chamber 3 leaks from the gap between the pressurized plunger 7 and the cylinder main body 6. It is provided via a check valve 20. Check valve 20
The ball valve body 20a normally closes the valve hole 20c of the valve seat 20b with the hydraulic pressure of the hydraulic oil in the hydraulic oil chamber 3, but when the hydraulic pressure decreases due to leakage of the hydraulic oil, the force of the spring 20d exceeds the hydraulic pressure. The ball valve element 20a separates from the valve seat 20b and the valve hole 20c
Is opened, and the hydraulic oil is supplied into the hydraulic oil chamber 3. The cylinder body 6 is provided with a hydraulic oil drain port 21 for discharging hydraulic oil leaked to the pressure spring 10 side.

In such a diaphragm pump, when the eccentric cam 13 presses the return piston 11 to compress the return spring 12 and free the pressure plunger 7, the pressure plunger is restored by the restoring force of the pressure spring 10. 7, the hydraulic oil is pressurized, and the diaphragm 4 is pushed out to the pump chamber 2 side, whereby the pressure of the liquid in the pump chamber 2 rises, and the check valve 8 at the inlet of the pump chamber 2 Is closed and the check valve 9 at the outlet of the pump chamber 2 is opened, so that the liquid in the pump chamber 2 is supplied to the supply destination. Next, when the eccentric cam 13 releases the pressing of the return piston 11 and performs a retreat operation, the return spring 12 having a larger restoring force than the restoring force of the pressure spring 10 becomes free, and the return spring 12
The return piston 11 is pushed out in the direction of the eccentric cam 13 by the restoring force of the pressure plunger 7, and the pressure plunger 7 is pulled back by the return operation of the return piston 11, and the pressure spring 10 is compressed by the return of the pressure plunger 7. Will be.

In this diaphragm pump, the pump chamber 2
Eccentric cam 13 with a force greater than the force required to pressurize the liquid inside
Has to compress the return spring 12, and in this case, it is necessary to take out a force larger than the rotation shaft 18, but after passing the vertex of the eccentric cam 13, the return spring 12
Since a rotational force is applied to 3, the pressurizing plunger 7 actually extracts only the work corresponding to the distance moved.

Since the pressurizing plunger 7 moves by the restoring force of the pressurizing spring 10 which has been compressed in advance, when the consumption of the pressurized liquid at the supply destination is small, the pressurizing plunger 7 is slightly moved and the inside of the pump chamber 2 moves. Since the pressure increases and balances with the pressing force of the pressure spring 10, the pressure of the hydraulic oil in the hydraulic oil chamber 3 does not increase excessively.

Since the return spring 12 has a function of returning the pressure spring 10 by the extension, the energy consumption can be reduced as compared with a method in which the pressure in the hydraulic oil chamber 3 is released by the relief valve.

Since the force for pressurizing the hydraulic oil is generated by the pressure spring 10, even if the discharge port is closed,
No excessive pressure is applied to the diaphragm 4.

When hydraulic oil leaks from the sliding surface of the pressurizing plunger 7 and the hydraulic oil chamber 3 becomes negative pressure, the check valve 20 opens and hydraulic oil is supplied from the hydraulic oil supply port 19 into the hydraulic oil chamber 3. Flows into.

FIG. 2 shows an example in which fuel is supplied to a two-cycle internal combustion engine 23 using a diaphragm pump 22 which is a modification of the diaphragm pump of the first example.

The two-stroke internal combustion engine 23 has a crankcase 24 at the lower part, on which a cylinder 25 is connected. The upper end of the cylinder 25 is connected to the cylinder head 2.
It is closed at 6. An injector 28 for supplying fuel to a combustion chamber 27 below the cylinder head 26 is provided.
And an ignition plug 29 for igniting the supplied fuel. A piston 31 is disposed in a cylinder chamber 30 in the cylinder 25 so as to be able to move up and down. Piston 3
1 is transmitted through a connecting rod 32 to convert a vertical movement into a rotational movement.
4 is provided in a crank chamber 34. The crank mechanism 33 supports a crank pin 35 that rotatably supports the other end of the connecting rod 32, a crank web 36 that supports the crank pin 35 eccentrically, and a center of the crank web 36. And a rotating shaft 18 composed of a crankshaft penetrating the crankcase 24 rotatably. An exhaust port 38 is provided at an intermediate portion of the cylinder 25. The cylinder 25 is provided with a plurality of scavenging ports 39 corresponding to the exhaust ports 38. These scavenging ports 39 are connected to scavenging passages 40.
And is communicated with the inside of the crankcase 24. An intake port 41 is provided in the crankcase 24, and the intake port 41 is closed by a reed valve 42.

In such a two-cycle internal combustion engine 23,
A diaphragm pump 22 is attached to supply fuel to the injector 28. In the diaphragm pump 22, the housing 1 housing the diaphragm 4 is formed separately from the liquid cylinder 5, and the hydraulic oil chamber 3A of the liquid cylinder 5 and the hydraulic oil chamber 3B on the diaphragm 4 side supply hydraulic oil. They are connected by a pipe 43. A roller 44 is rotatably supported at the tip of the return piston 11, and the return piston 11 is in contact with the outer periphery of the eccentric cam 13 via the roller 44. The outlet of the pump chamber 2 is connected by a high-pressure fuel pipe 45. Other configurations of the diaphragm pump 22 are the same as those in FIG.

According to such a diaphragm pump 22, the housing 1 containing the diaphragm 4 can be arranged close to the injector 28 to which the fuel is supplied, and the injector 28 to which the fuel is supplied from the housing 1 containing the diaphragm 4. The length of the high-pressure fuel pipe 45, which is the supply pipe for the pressurized fuel, can be reduced. Further, the pipe connecting the housing 1 containing the diaphragm 4 and the liquid cylinder 5 is a hydraulic oil supply pipe 43 for supplying a hardly combustible hydraulic oil. Therefore, even if the pipe 43 is cracked and the hydraulic oil blows out, it explodes. There is no typical combustion.

FIGS. 3 and 4 are a vertical sectional view showing a second example of the embodiment of the diaphragm pump according to the present invention and an enlarged view showing different operation states of main parts thereof.

In this diaphragm pump, the liquid cylinder 5 slides in a pressure spring 10 which urges the pressure plunger 7 in the forward direction, and into a cylindrical portion 7a at the base end of the pressure plunger 7. A return rod 46 that is freely inserted and frees the pressure plunger 7 without pressing when pressed from the outside, but pulls back the pressure plunger 7 by a return operation when the pressure is released; The return rod 46
Is pressed periodically in the direction of the pressurizing plunger 7 and a return rod pressing cam 47 for releasing the pressing to perform a retreat operation, and a return rod 46 for the return rod pressing cam 47 to perform a retreat operation. And a return rod return mechanism 48 for pulling back in the retracting direction. At the base end of the return rod 46, there is provided a stopper 49 for returning the pressurized plunger 7, and this stopper 49 is engaged with the distal end of the cylindrical portion 7a when the pressurized plunger 7 is retracted. A hook 50 is integrally provided at the tip of the return rod 46. The return rod pressing cam 47 is integrally fixed to the outer periphery of the rotary shaft 18 formed of a crankshaft, and is driven to rotate as the rotary shaft 18 rotates. Return rod return mechanism 4
8 is integrally fixed to the outer periphery of the rotating shaft 18 and
The return cam 51 is rotated by the rotation of the rotary cam 8, and the rocker arm 52 is operated by the return cam 51, is hooked on the hook 50, and pulls back the return rod 46. The rocker arm 52 is integrally fixed to the outer periphery of a rotation shaft 53 in a direction parallel to the rotation shaft 18, one end of the rocker arm 52 is operated by being brought into contact with the return cam 51, and the other end is hooked by the return rod 46. The return rod 46 is pulled back by the clockwise rotation of the rocker arm 52 by being hooked by 50, and the pressurizing plunger 7 is pulled back via the stopper 49.

In such a diaphragm pump 22,
When the return rod pushing cam 47 pushes the return rod 46 and pushes it into the pressure plunger 7 to release the pressure plunger 7, the pressure plunger 7 is pushed out by the restoring force of the pressure spring 10. The hydraulic oil is pressurized, and the diaphragm 4 is pushed out to the pump chamber 2 side, whereby the pressure of the liquid in the pump chamber 2 rises, the check valve 8 at the inlet of the pump chamber 2 closes, and the pump chamber 2 closes. The check valve 9 at the outlet 2 is opened, and the liquid in the pump chamber 2 is supplied to the supply destination. Next, when the return rod pushing cam 47 releases the pressing of the return rod 46 and performs the retreat operation, when the return rod return mechanism 48 performs the return operation of pulling out the return rod 46 from the pressure plunger 7, the return rod 46
The pressurizing plunger 7 is pulled back by the return operation, and the pressurizing spring 10 is compressed by the retraction of the pressurizing plunger 7.

For this reason, the same effect as described above can be obtained in the diaphragm pump 22 as well.

In this diaphragm pump 22, the strong return spring 12 required in the diaphragm pump 22 of the first example is not required.

It should be noted that the diaphragm pump 22 also
As shown in FIG. 2, the housing 1 containing the diaphragm 4 is formed separately from the liquid cylinder 5, and the hydraulic oil chamber 3A of the liquid cylinder 5 and the hydraulic oil chamber 3B on the diaphragm 4 side are connected to a hydraulic oil supply pipe. A structure for connecting at 43 can be provided.

[0049]

According to the diaphragm pump of the present invention,
Since the pressurizing plunger is pushed out only by the restoring force of the pressurizing spring and presses the diaphragm toward the pump chamber side via the hydraulic oil, the liquid is pumped from the pump chamber to a predetermined pressure by an amount required by the supply destination. Can be supplied.

Further, in this diaphragm pump, the pressure plunger moves to supplement only the liquid consumed by the supply destination, so that a pressure regulator for the pressurized liquid is not required, and the cost can be reduced.

Also, in this diaphragm pump, the pressure plunger is advanced by the restoring force of the pressure spring, so that the pressure of the pressurized liquid does not rise abnormally, and a safety valve and a relief valve are not required.

Further, in the diaphragm pump according to the present invention, when the squeezing plunger is slidably inserted into the cylindrical portion of the pressurizing plunger and is pressed from the outside, the pressing plunger is free without being pressed, but the pressure is reduced. A return rod that pulls back the pressure plunger in a return operation when released, a return rod pushing cam that periodically presses the return rod in the direction of the pressure plunger and releases the pressure to perform a retreat operation And a return rod return mechanism for retracting the return rod in the retracting direction when the return rod pushing cam performs the retracting operation, the same effect as described above can be obtained, and a strong return spring is not required. It can be.

In the diaphragm pump according to the present invention, the housing accommodating the diaphragm is formed separately from the liquid cylinder, and the hydraulic oil chamber of the liquid cylinder and the hydraulic oil chamber of the diaphragm are connected by a hydraulic oil supply pipe. The housing accommodating the diaphragm can be arranged close to the liquid supply destination, and the length of the pressurized liquid supply pipe from the housing accommodating the diaphragm to the liquid supply destination can be shortened. In addition, the piping connecting the housing containing the diaphragm and the liquid cylinder is hydraulic oil supply piping that supplies hydraulic oil that is difficult to burn, so even if this piping cracks and hydraulic oil blows out, explosive combustion may occur. There is no.

In the diaphragm pump according to the present invention, if a hydraulic oil supply port for supplying hydraulic oil to the hydraulic oil chamber is provided via a check valve, the hydraulic oil in the hydraulic oil chamber slides on the pressurized plunger. Even if it leaks from the surface, it can be automatically replenished.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional view showing an example in which fuel is supplied to a two-cycle internal combustion engine using a diaphragm pump obtained by modifying the diaphragm pump of the first example.

FIG. 3 is a longitudinal sectional view showing a second example of the embodiment of the diaphragm pump according to the present invention.

FIG. 4 is an enlarged view showing a different operation state of a main part of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Pump chamber 3, 3A, 3B Hydraulic oil chamber 4 Diaphragm 5 Liquid cylinder 6 Cylinder main body 7 Pressurizing plunger 7a Cylindrical part 8, 9 Check valve 8a, 9a Ball valve body 8b, 9b Valve seat 8c, 9c Valve Hole 10 Pressure spring 11 Return piston 12 Return spring 13 Eccentric cam 14 Piston ring 15, 16 Spring receiver 17 Stopper 18 Rotating shaft 19 Hydraulic oil supply port 20 Check valve 20a Ball valve body 20b Valve seat 20c Valve hole 21 Hydraulic oil drain Mouth 22 Diaphragm pump 23 Two-cycle internal combustion engine 24 Crankcase 25 Cylinder 26 Cylinder head 27 Combustion chamber 28 Injector 29 Spark plug 30 Cylinder chamber 31 Piston 32 Connecting rod 33 Crank mechanism 34 Crank chamber 35 Crank pin 36 Crank web 38 Exhaust Port 39 Scavenging port 40 Scavenging passage 41 Intake port 42 Reed valve 43 Hydraulic oil supply pipe 44 Roller 45 High pressure fuel pipe 46 Return rod 47 Return rod pushing cam 48 Return rod return mechanism 49 Stopper 50 Hook section 51 Return cam 52 Rocker arm 53 Axis of rotation

Claims (4)

[Claims] A diaphragm for separating a pump chamber and a hydraulic oil chamber in a housing is operated by a pressure plunger of a liquid cylinder connected to the hydraulic oil chamber, and the diaphragm is bent toward the pump chamber. A diaphragm pump for closing the check valve at the inlet of the pump chamber and opening the check valve at the outlet of the pump chamber to send out the liquid in the pump chamber, wherein the liquid cylinder moves the pressurizing plunger forward. A pressurizing spring that is urged against, and a return piston that does not press the pressurizing plunger when pressed from the outside but retracts the pressurizing plunger in a return operation when the pressing is released, The return piston is urged with a restoring force greater than the restoring force of the pressurizing spring in a direction to return, and is compressed when a pressing force is applied to the return piston from outside. A return spring that does not apply a return force to the pressurizing plunger; and an eccentric cam that performs an operation of pressing the return piston in the direction of the pressurizing plunger and releases the pressing to perform a retracting operation. Diaphragm pump. 2. A diaphragm for partitioning a pump chamber and a hydraulic oil chamber in a housing is operated by a pressure plunger of a liquid cylinder connected to the hydraulic oil chamber, and the diaphragm is bent toward the pump chamber. A diaphragm pump for closing the check valve at the inlet of the pump chamber and opening the check valve at the outlet of the pump chamber to send out the liquid in the pump chamber, wherein the liquid cylinder moves the pressurizing plunger forward. A pressure spring biasing the pressure plunger, which is slidably inserted into the cylindrical portion of the pressure plunger and is free without pressing the pressure plunger when pressed from outside, A return rod that pulls back the pressure plunger in a return operation when the pressing is released, an operation of periodically pressing the return rod in the direction of the pressure plunger, and the pressing thereof A cam pushing back rod performs a save operation to release, said return and the rod pressing diaphragm pump characterized by having a return rod return mechanism cam pulls back the return rod when performing the save operation to the retreat direction. 3. The housing accommodating the diaphragm is formed separately from the liquid cylinder, and the hydraulic oil chamber of the liquid cylinder and the hydraulic oil chamber of the diaphragm are connected by a hydraulic oil supply pipe. The diaphragm pump according to claim 1 or 2, wherein 4. The diaphragm pump according to claim 1, wherein a hydraulic oil supply port for supplying the hydraulic oil to the hydraulic oil chamber is provided through a check valve.