JPS6117040Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid dispensing device that does not generate droplets at the tip of the opening of a discharge tube.

Conventionally, as a device for mechanically measuring and dispensing liquids such as reagent solutions used in chemical laboratories, etc., as shown in FIG. A discharge pipe 4 that opens above the receiving tank 3 is connected to the head of a cylinder 7 via check valves 5 and 6, respectively, and a plunger holder is provided at the right end of a suction/discharge plunger 8 that reciprocates within the cylinder 7. A cam follower 13 consisting of a roller attached to the right end of the holding body is attached to a driving rotating shaft 14 of a speed reduction mechanism (not shown) by an electric motor (not shown) facing an appropriate position behind the cam follower 13. The eccentric cam 15 is brought into contact with the elastic force of the push spring 16, and the eccentric cam 1 is brought into contact with the eccentric cam 15 through this contact point.
By converting the eccentric rotational movement of the plunger 5 into a reciprocating movement of the plunger 8, the liquid is dispensed through the check valves 5 and 6, and the displacement of the plunger is changed arbitrarily by resisting the push spring 16. By providing a limit screw 17 on the plunger holder 10 and screwing the limit screw 17 with its knob 18, the plunger holder 1
A device is known that arbitrarily adjusts the interval at which the cam 15 contacts the side edge of the eccentric cam 15 during eccentric rotation.

However, in this device, when the discharge is about to end, the forward movement of the piston 8 becomes slow, the discharge flow velocity becomes small, and droplets are generated at the open end of the discharge pipe 4, and these droplets are caused by vibrations and other causes. Therefore, if the liquid falls into the dispensing liquid receiving tank 3, the dispensing error increases and the reliability of the analysis value decreases, which is a major drawback.

The present invention was devised to eliminate the drawbacks of conventional devices of this type, and is designed to suddenly stop the forward movement of the plunger during the discharge process.
The purpose is to prevent the generation of droplets at the open end of the discharge pipe, and the configuration of the present invention to achieve this purpose is shown in FIGS. 1 and 3 corresponding to the embodiments. To explain, liquid tank 1
A suction pipe 2 that communicates with
The outer end of a suction/discharge plunger 8 that communicates with the head of the cylinder 7 and reciprocates within the cylinder 7 is connected to the plunger holder 10,
The plunger holder 10 is biased in the direction of pulling out the plunger 8 with a spring 16 for pulling out the plunger, and the cam follower 13 is supported by the plunger holder 10, and the cam follower 13 is rotated for driving. In a liquid dispensing device in which the plunger 8 is brought into contact with the outer periphery of an eccentric cam 15 fixed to a shaft 14 and reciprocated in accordance with the rotation of the eccentric cam 15, the reciprocating motion with respect to the plunger holder 10 is provided. An operating rod 12 is supported movably in the operating direction and substantially the moving direction, the cam follower 13 is attached to the operating rod 12, and the operating rod 12 is attached to the plunger holder 1.
0, a push spring 11 having a stronger elasticity than the spring 16 for pulling out the plunger is energized toward the eccentric cam 15, and the contact position of the eccentric cam 15 with the cam follower 13 is adjusted to the outer periphery of the eccentric cam. The liquid dispensing device is characterized in that the movement of the plunger holder 10 in the plunger pushing direction is restricted before reaching the end of the pushing cam surface C.

The present invention will be described above with reference to the accompanying drawings.

FIG. 1 is a schematic explanatory diagram showing an embodiment of the present invention. Reference numeral 9 denotes a cylindrical hole provided vertically in the plunger holder 10, and inside this is a push spring 11 having a stronger elasticity than the push spring 16;
The operating rod 12, which is always resilient, is slidably pushed in by this spring, and the operating rod 12 comes into contact with the eccentric cam 15 via the cam follower 13. In addition,
Other numbers indicate the same parts as in FIG.

Therefore, when the eccentric cam 15 now attached to the drive rotating shaft 14 is rotated clockwise as shown by arrow a by an electric motor and a speed reduction mechanism (not shown), the cam follower 13, operating rod 12, and push spring 1 that come into contact with the eccentric cam 15 are rotated clockwise as shown by arrow a.
1. The plunger holder 10 and the plunger 8 move forward together against the elastic force of the push spring 16, and dispense the liquid in the cylinder 7 through the check valve 6 and the discharge pipe 4. Discharge into liquid receiving tank 3,
Dispense. The eccentric cam 15 used here may have any shape, for example, as shown in FIG.
One example is one in which the pushing cam surface C is formed within a constant angle range of approximately 180 degrees. If these cams are rotated at a constant speed in the direction of the arrow a, each pushing cam surface C can push the plunger 8 forward at a constant speed.

When the cam follower 13 is in contact with the pushing cam surface C, that is, when the piston is pushing forward, a part or the whole of the plunger holder 10 is stopped, for example, on the opening end surface of the cylinder 7. If the plunger 8 connected to the holding body is suddenly stopped by colliding with the cylinder 7, the discharge can be abruptly stopped. Not only can the liquid be dispensed well, but also the generation of droplets at the open end of the discharge tube 4 can be prevented.

Then, the plunger 8 and the plunger holder 10 abruptly stop the forward pushing movement, but the cam follower 13 and the operating rod 12 can push further against the elastic force of the push spring 11. , rotation of the eccentric cam 15 cannot be prevented.

Next, when the drive rotating shaft 14 further rotates and the eccentric cam 15 rotates, the cam follower 1 first
3 and the operating rod 12 are returned to their original positions by the elastic force of the push spring 11, and when the eccentric cam 15 further rotates, the cam follower 13, the operating rod 12,
The push spring 11, the plunger holder 10, and the plunger 8 are pushed back together by the push spring 16, and the liquid in the liquid tank 1 is sucked and collected into the cylinder 7 via the suction pipe 2 and the check valve 5. Ru.

The previously described operations can then be repeated and the dispensing of liquid can be carried out repeatedly.

In addition, when adjusting the dispensed amount, by screwing the control screw 17 with the knob 18, the interval at which the plunger holder 10 contacts the side edge of the eccentric cam 15 during eccentric rotation can be arbitrarily adjusted. 8 may be controlled arbitrarily.

The present invention is constructed as described above, and has an operating rod 12 supported movably in the reciprocating direction and substantially in the direction of movement relative to the plunger holder 10.
At the same time, the cam follower 13 is attached to the plunger holder 10, and the operating rod 12 is urged toward the eccentric cam 15 by using a push spring 11 that is more elastic than the spring 16 for pulling out the plunger. 15 is in contact with the cam follower 13 on the pushing cam surface C of the outer periphery of the eccentric cam.
Since the movement of the plunger holder 10 in the plunger pushing direction is restricted before reaching the end of the plunger, the plunger is suddenly stopped in the middle of the pushing movement of the plunger by the pushing cam surface C. Therefore, the dispensed liquid within the tip of the discharge tube 4 will fly out due to its own inertia, thereby preventing the generation of droplets at the discharge tube opening and improving the dispensing accuracy. This has resulted in a significant improvement in the reliability of analytical values.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram showing a liquid dispensing device of the present invention, Fig. 2 is a schematic explanatory diagram showing a conventional liquid dispensing device, and Fig. 3 is an enlarged explanatory diagram showing a specific example of an eccentric cam. It is a diagram. 1...Liquid tank, 2...Suction pipe, 4...Discharge pipe,
5, 6... Check valve, 7... Cylinder, 8... Plunger, 9... Cylindrical hole, 10... Plunger holder, 11... Push spring, 12... Operating rod, 13... Cam Follower, 14... Drive rotation shaft, 15... Eccentric cam, 16... Push spring.

Claims (1)

[Scope of utility model registration request] A suction pipe 2 that communicates with the liquid tank 1 and a discharge pipe 4 that opens above the dispensed liquid receiving tank 3 are connected to each other by a check valve 5.
and 6 to the head of cylinder 7,
The outer end of the suction/discharge plunger 8 that reciprocates within the cylinder 7 is connected to a plunger holder 10, and the plunger holder 10 has a spring 16 for pulling out the plunger in a direction in which the plunger 8 is pulled out. At the same time, the cam follower 13 is supported by the plunger holder 10, and the cam follower 13 is brought into contact with the outer periphery of the eccentric cam 15 fixed to the drive rotating shaft 14. In a liquid dispensing device configured to reciprocate the plunger 8 according to the
An operating rod 12 is supported on the plunger holder 10 so as to be movable in the reciprocating direction and substantially in the moving direction, the cam follower 13 is attached to the operating rod 12, and the operating rod 12 is attached to the plunger holder 10. 10, a push spring 11 having a stronger elasticity than the spring 16 for pulling out the plunger is biased toward the eccentric cam 15, so that the contact position of the eccentric cam 15 with the cam follower 13 is adjusted to the outer periphery of the eccentric cam. A liquid dispensing device characterized in that the movement of the plunger holder 10 in the plunger pushing direction is restricted before reaching the end of the pushing cam surface.