JPS6143553B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a liquid feeding pump, and particularly to a plunger type liquid feeding pump.

[Conventional technology]

Conventionally, as a plunger type liquid sending pump, for example, a continuous minute liquid drainage pump described in Japanese Utility Model Publication No. 40-29406 is known.

This continuous micro-drainage pump has a cam fixed to the shaft of a worm wheel that is rotated by a worm attached to the main shaft so as to alternately push up two plungers that are pulled down by a spring. Attach the drive rod to the shaft of the worm wheel,
A four-way switching plug connecting each cylinder to the suction passage and the discharge passage is attached to the upper end of the shaft of the partially geared gear, which has teeth at four equally spaced locations that mesh with the regular gear provided on the main shaft. A driven rod driven by the driving rod is attached to the lower end of the shaft so that the vertical and horizontal directions intersect vertically, and one end is fixed to the shaft and the other end is pulled by a spring. It is configured to support a partially geared gear.

In the above-mentioned continuous micro-drainage pump, each plunger is alternately pushed up by rotating the cam on the shaft of the worm wheel in accordance with the rotation of the main shaft, and is pulled down by a spring, so that each pump is connected to the suction passage and the discharge passage. are repeated alternately, and the driven rod is driven by the rotation of the driving rod as the cam rotates, and the missing gear meshes with the regular gear, and the switching taps are intermittently switched. The suction passage and the discharge passage are connected alternately, and the liquid is continuously drained in minute amounts.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional plunger-type liquid transfer pump, although it is desirable that there is no dead volume between the plunger and the inner bottom of the cylinder at the stroke end (top dead center) of the discharge stroke, it is necessary to Since it is difficult to meet this requirement, a gap is provided between the plunger at top dead center and the inner bottom of the cylinder, and
Since there is play in the drive system of the plunger, the top dead center of the plunger fluctuates due to fluctuations in the moving speed of the plunger, and water drainage at the tip of the discharge nozzle becomes difficult, resulting in inaccurate liquid delivery amount. be.

In addition, since the four-way switch is switched while the plunger is moving, and the suction passage and discharge passage are temporarily closed by the switching valve, backflow of liquid may occur.
There is a problem with abnormal pressure being applied to the cylinder or plunger.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a liquid feeding pump which is capable of accurately feeding the amount of liquid and which also allows good connection between a cylinder and a suction path and a discharge path.

[Means for solving problems]

In order to solve the above-mentioned problems, this invention includes a plunger that can come into contact with the inner bottom of the cylinder and has an elongated hole in the cylinder axis direction at the outer end, and an eccentric that has an elongated hole in the radial direction. An eccentric outer ring, a pin inserted into each elongated hole to connect the plunger and the eccentric outer ring, a spring that pulls the pin toward the inner bottom of the cylinder, and interposed between the cylinder and the suction passage and the discharge passage, It consists of an on-off valve that is operated at each stroke end of the plunger.

[Effect]

Even if the eccentric outer ring starts to move forward at the beginning of the discharge stroke, the plunger is held in a stopped state for a required period of time by the action of the elongated hole, and the on-off valve is operated during the stop period of the plunger, and during the discharge stroke Even after the plunger contacts the inner bottom of the cylinder at the end and suddenly stops, the eccentric outer ring is moved forward by the required amount due to the action of the elongated hole, and the plunger remains in contact with the inner bottom of the cylinder due to the action of the spring. is maintained. Furthermore, even if the eccentric outer ring starts to move forward at the beginning of the suction stroke, the plunger is held in a stopped state for a required period of time by the action of the elongated hole, and the on-off valve is operated while the plunger is stopped.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

A cylinder 4 is fixed to the pump body 2 of the liquid transfer pump, and a plunger 6, which is kept liquid-tight by packing 8, has its inner end abutted against the inner bottom of the cylinder 4. It is possible to be mated. At the outer end of the plunger 6,
One end of the connecting member 10 protruding into the pump body 2 is integrally connected, and the other end 14 of the connecting member is provided with a long hole 12 extending in the cylinder axis direction.

On the other hand, a main shaft 20 that is perpendicular to the cylinder axis is horizontally suspended in the pump main body 2 by a bearing, and a driven gear 22 fixed to the outside of one end of the main shaft 20 is connected to a rotary drive device 16 fixed to the pump main body 2. It meshes with a driving gear 18 fixed to the drive shaft.
An eccentric inner ring 24, which constitutes a part of an eccentric, is provided on the main shaft 20 to face the other end 14 of the connecting member 10, and an oval eccentric outer ring 28 is attached to the eccentric inner ring 24. It is fitted through 23. At the tip of the eccentric outer ring 28, opposing plate-shaped connecting portions 25 and 26 are formed by cutting the tip at right angles to the main shaft 20. Radial long hole 2
7 and 29 are provided. And eccentric outer ring 2
8 and the connecting member 10 are the long hole 12 of the other end 14 of the connecting member 10 inserted between the connecting parts 25, 26 of the eccentric outer ring 28 and the connecting parts 25, 2 of the eccentric outer ring 28.
It is connected by a pin 34 inserted through long holes 27 and 29 of 6. The pin 34 has locking pins 3 implanted at both ends of the pin 34 and at each connecting portion 25, 26.
Tension springs 32 and 33 stretched between 0 and 31
As a result, the connecting member 10 is pulled toward one end of the connecting member 10, in other words, toward the inner bottom of the cylinder 4.

A cam disk 36 is fixed to the other end of the main shaft 20, and cam pins 38 and 40 are implanted around the periphery of the cam disk 36 to drive a follower, which will be described later, at each stroke end of the plunger 6. It is set up. On the other hand, in the pump body 2, a support shaft 46 is installed at one end of a rectangular plate-shaped follower 42 that is swung by the cam pins 38 and 40.
4, and this cam follower 4
2 is a rectangular opening 4 provided near the other end.
The cam pins 38 and 40 are engaged with the cam pins 38 and 40 via trapezoidal guide protrusions 50 and 52 formed on the opposing upper and lower sides of the cam pins 8 (see FIG. 3A).

A valve body 56 of an on-off valve interposed between the cylinder 4 and the suction and discharge passages is fixed to the pump body 2 as described later. As shown in FIG. 4, the valve body 56 has connectors 58, 60,
62, 64, and four L-shaped channels 68, 7 whose other ends are open to a sliding surface that slides in contact with the valve body 66;
0, 72, and 74 are provided. One ends of the first and fourth channels 68, 74 are connected to the discharge channel and the suction channel, respectively, via liquid feed pipes 76, 78 connected to the connectors 58, 64, and the second and third channels 7
As shown in FIG. 2, one ends of the tubes 0 and 72 are connected to the top inside the cylinder 4 via liquid feed pipes 80 and 82 connected to connectors 60 and 62, respectively.

A valve shaft 86 is inserted into the axial center of the valve body 56 of the on-off valve, and a valve body 66 to which an oval operating lever 84 is fixed is rotatably fitted into the valve shaft 86. has been done. Then, the valve body 66 is
0 through a thrust bearing 88. The sliding surface of the valve body 66 with the valve body 56 has the other end of the first flow path 68, the other end of the second flow path 70, the other end of the third flow path 72, and the fourth flow path. Grooves 92 and 94 having lengths and widths suitable for connecting the other ends of 74 are provided, respectively. A notch 96 is formed at the tip of the operating lever 84, and the follower 42 is inserted into this notch 96.
An engagement pin 98 implanted in the center of the other end is engaged. The grooves 92 and 94 rotate together with the valve body 66 when the operating lever 84 is rotated in conjunction with the rocking of the follower 42, and the grooves 92 and 94 rotate together with the valve body 66 at the positions indicated by the broken line and the dashed line in FIG. while the first and second channels 68, 70 are in communication, the third and fourth channels 72, 74 are out of communication, and the third and fourth channels 68, 70 are in communication with each other. The first and second channels 68, 70 are provided so as to be out of communication while the channels 72, 74 are in communication.

Note that the disk 10 fixed to one end of the main shaft 20
A magnet 102 is attached to one place on the circumferential surface of 0,
A reed switch 124 is fixed to the pump body 2 and is opened and closed each time the magnet 102 passes nearby. There is.

Next, the operation of the liquid pump will be explained.

When the main shaft 20 is rotated at a constant speed in a certain direction by the operation of the rotational drive device 16, the eccentric outer ring 2 of the eccentric
8 causes the plunger 6 to reciprocate and is stopped for a required period at each stroke end, and during each stop period of the plunger 6, the valve body 66 of the on-off valve is rotated by the rocking of the follower 42 by the cam pins 38, 40. The suction and discharge of the feeding body are repeated.

That is, as shown in FIG. 3A, the plunger 6 is now at the stroke end (bottom dead center) of the suction stroke.
, the pin 34 is located at the left end of the elongated hole 12 of the connecting member 10, and the other end of the follower 42 is moved upward, and the cam pins 38, 40
It is assumed that the valve body 66 of the on-off valve is at rest so that the difference 92, 94 is in the position shown in the dashed line in FIG. When the main shaft 20 is rotated in the direction of the arrow from the state shown in FIG. 3A, the eccentric outer ring 28 starts to move rightward, but the pin 34 of the plunger 6 is fixed to the connecting member 10 as shown in FIG. 3B. While the plunger 6 is not moved until it comes into contact with the right end of the elongated hole 12, the cam pin 38 pushes down the guide protrusion 52 and rotates the other end of the follower 42 downward while the plunger 6 is stopped. So,
The tip of the operating lever 84 of the opening/closing valve is rotated downward by the engagement pin 98, and the differentials 92 and 94 are moved to the position shown by the broken line, thereby opening and closing the channels 68, 70, 72, and 74.

When the state shown in FIG. 3B shifts to the state shown in FIG. 3C as the main shaft 20 rotates, the plunger 6
Due to the forward movement of the eccentric outer ring 28, it is moved in the same direction via the pin 34, and the liquid in the cylinder 4 is transferred to the liquid sending pipe 8.
0, the liquid is discharged through the second flow path 70, the groove 92, the first flow path 68, and the liquid feeding pipe 76 to the discharge path, and suddenly reaches the dead point where the inner end abuts the inner bottom of the cylinder 4. will be stopped. During this time, the valve body 66 of the on-off valve is pressed against the valve body 56 by the flat spring 90, so that it is held stationary by the friction of the sliding surfaces thereof.

When the main shaft 20 is further rotated from the state shown in FIG. 3C, the plunger 6 reaches the top dead center and the pin 34
Since the movement of the eccentric outer ring 28 is prevented by the right end of the elongated hole 12 of the connecting member 10, the eccentric outer ring 28 is moved forward while stretching the tension springs 32 and 33, and shifts to the state shown in FIG. 3D. At this time, since the plunger 6 is pulled toward the inner bottom of the cylinder by the tension springs 32 and 33, its inner end comes into pressure contact with the inner bottom of the cylinder 4, and the liquid in the cylinder 4 is completely discharged.

When transitioning from the state shown in FIG. 3D to the state shown in FIG. 3E, as the eccentric outer ring 28 starts to return to the left, the tension springs 32 and 33 are returned and contracted, and the pin 34 is extended to the length of the eccentric outer ring 28. After being brought into contact with the right end portions of the holes 27 and 29, the plunger 6 is further brought into contact with the left end portion of the elongated hole 12 of the connecting member 10, but during this time, the plunger 6
While the plunger 6 is held in a stopped state, the cam pin 38 pushes up the guide protrusion 50 and rotates the other end of the follower 42 upward during the period when the plunger 6 is stopped. 84
The tips of the channels 72, 74, 6 are rotated upward, and the grooves 92, 94 are moved to the positions shown by the dashed lines.
8,70 on-off valves are performed.

When the main shaft 20 is further rotated from the state shown in FIG. 3E, the eccentric outer ring 28 moves in the same direction via the pin 34, and the liquid from the suction path is transferred to the liquid sending pipe 78 and the fourth The liquid is sucked into the plunger 4 through the flow path 74, the groove 94, the third flow path 72, and the liquid feeding pipe 82, and is stopped in the state shown in FIG. 3 when it reaches the bottom dead center.
During this time, the valve body 66 of the on-off valve is held stationary by being pressed against the valve body 56 by the spring 90, as in the case of the discharge stroke of the plunger 6.

The operation of the liquid pump described above is summarized in FIG. In the figure, the horizontal axis represents the rotation angle of the main shaft 20, and the vertical axis represents the amount of movement of the eccentric outer ring 28 and the plunger 6. The sine waveform shown by the broken line represents the movement of the eccentric outer ring 28, and the solid line represents the movement of the eccentric outer ring 28. 6 movement is shown. The symbols A, B, C, D, E, and A shown below refer to Figure 3A, Figure 3B, and Figure 3C, respectively.
3D, 3E, and 3A.

As can be understood from Fig. 5, the plunger 6
is stopped from when the eccentric outer ring 28 starts moving forward at time A until it reaches time B, and the on-off valve is operated during this time. The plunger 6 starts its discharge stroke from time B, is moved at a required speed until time C, and suddenly stops when it comes into contact with the inner bottom of the cylinder 4. This sudden stop will cause the liquid flowing at the required flow rate to suddenly stop at the end of the discharge stroke, so for example, when delivering a small amount of liquid, a droplet will appear at the tip of the discharge nozzle. In other words, the end surface of the liquid at the nozzle tip can be kept in a retracted state without creating a
The accuracy of quantitative determination of the amount of liquid to be sent is improved.

The plunger 6 is stopped from time C to time E, and the eccentric outer ring 28 starts to move back from time D during this period, and the opening/closing valve is opened and closed from time D to time E. Then, the plunger 6 starts the suction stroke from time E, and
At this point, it is stopped, and thereafter, the same operation is repeated to perform continuous liquid feeding.

In the above embodiment, a case has been described in which the main shaft 20 is rotated in a fixed direction and the follower 42 is swung by one of the cam pins 38 to operate the operating lever 84. However, it is also possible to rotate the main shaft 20 in the opposite direction. the follower 4 by the other cam pin 40.
By swinging 2 and operating the operating lever 84, the liquid is fed in the opposite direction to the above-mentioned direction.

Therefore, by arbitrarily selecting the rotational direction of the main shaft 20, the liquid feeding direction can be freely set.

〔Effect of the invention〕

As described above, according to the present invention, unlike conventional pumps, there is no dead volume between the inner end of the plunger and the inner bottom of the plunger at the top dead center, and the plunger is moved closer to the inner bottom of the cylinder at the top dead center. Since the plunger suddenly stops when it comes into contact with the plunger, the stopping position of the plunger is always constant, and no droplets are generated at the tip of the discharge nozzle. ), the amount of liquid delivered can be made extremely accurate. In addition, the plunger is stopped for the required period at each stroke end, and the on-off valve is operated during this stop period, so there is no backflow or abnormal pressure applied to the cylinder etc. as with conventional pumps, and the cylinder The suction passage and the discharge passage can be well connected to each other.

[Brief explanation of the drawing]

The drawings show an embodiment of the liquid pump according to the present invention, in which Fig. 1 is a plan sectional view, Fig. 2 is a front view of the cylinder in section, and Figs. 3A to 3E each show the operating state. FIG. 4 is an explanatory diagram of the on-off valve, and FIG. 5 is a diagram showing the operation timing of the eccentric outer ring and the plunger. 4...Cylinder, 6...Plunger, 10...
Connection member, 12... Elongated hole, 16... Rotation drive device, 20... Main shaft, 24... Eccentric inner ring, 27, 2
9... Long hole, 28... Eccentric outer ring, 30, 31...
Locking pin, 32, 33... tension spring, 34... pin, 36... cam disk, 38, 40... cam pin, 42... follower, 50, 52... guide protrusion, 56... valve body , 66... Valve body, 84... Operation lever, 96... Notch, 98... Engagement pin.

Claims (1)

[Claims] 1. A plunger that can come into contact with the inner bottom of the cylinder and has a long hole in the cylinder axis direction at its outer end, and an eccentric outer ring of an eccentric that has a radial long hole in the outer end.
A pin inserted into each elongated hole to connect the plunger and the eccentric outer ring, a spring that pulls the pin toward the inner bottom of the cylinder, and a spring interposed between the cylinder and the suction passage and the discharge passage, each stroke of the plunger. A liquid sending pump characterized by comprising an on-off valve operated at an end.