JPH0116026Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a liquid dispensing device such as a dispenser or pipette. More specifically, this invention relates to a liquid dispenser that is highly accurate and easy to reduce costs.

Conventionally, in cylinder-type liquid dispensers, including variable capacity types, the piston or rod is driven by first transmitting the rotation of a pulse motor to a screw shaft, and then moving the rotation of this screw shaft through a nut screwed onto it. Instead of linear movement of the member, it has been carried out by interlocking a piston or rod with the moving member. However, with this drive method, there is not only friction loss at the threaded part of the screw and nut, but also power loss when converting the rotational motion of the nut into linear motion, which significantly deteriorates the torque transmission efficiency. As motors become larger, in order to improve the accuracy of liquid dispensers, expensive threaded shafts and nuts with less backlash must be used.
The drawback was that the cost was relatively high.

This idea eliminates the above drawbacks,
A liquid dispensing system that allows the rotation of a pulse motor to be converted into linear motion with less backlash without using expensive screw shafts and nuts, and that improves torque transmission efficiency and allows the pulse motor to be made smaller. The purpose is to provide equipment.

This invention will be explained in detail below based on the embodiments shown in the figures. Note that this invention is not limited by this.

In FIGS. 1 to 3, a liquid dispenser 1 has a cylinder 4 attached to a rotating shaft 3 of a pulse motor 2.
A belt 6, a part of which is fixed to the surface of the cylinder 4 by screws 5 and wound so as not to overlap, and guides arranged such that both ends of the belt 6 are attached by screws 7 and 8 and are opposed to each other. The moving member 1 is slidably held in each guide groove 11, 12 of the parts 9, 10.
3, and a piston or rod 14 that is attached to one end of the movable member 13 in the direction of movement of the movable member 13 and is enclosed within the pump portion 15 to reciprocate.

The belt 6 is usually made of a stainless steel plate with a thickness of about 50 to 100 μm, and the belt 6 has elongated holes 16, as shown in FIG. A wide portion 6a and a narrow portion 6 that can fit into the long hole 16
It is formed from b. The winding on the surface of the cylinder 4 is as follows:
The belt 6 is fixed to the surface of the cylinder 4 with the screw 5 at the hole 17 provided in the center thereof, and the narrow part 6b
are inserted into the long holes 16 of the wide portion 6a and wrapped around the surface of the cylinder 4 so as to intersect with each other, as shown in FIG.
A hole 18 at one end of the wide portion 6a is attached to the upper surface of one end of the moving member 13 using a screw 7, and a hole 19 provided at one end of the narrow portion 6b is bent and attached to the back side of the other end of the moving member 13 using a screw 8. In this case, in order to improve the precision of the liquid dispenser 1 by eliminating slippage between the belt 6 and the moving member 13 when the pulse motor 2 rotates, it is necessary to wrap the belt in an arc shape on the other end of the moving member 13. If the bent leaf spring 20 is attached and the narrow portion 6b of the belt 6 is bent from above the leaf spring 20 to the back side of the moving member 13, the leaf spring 2
It is advantageous to be able to tension the belt 6 with zero elasticity. The attachment position of the leaf spring 20 is not limited to the above case, and biasing means other than the leaf spring 20 may be used.

In the above embodiment, the belt 6 is wound directly around the cylinder 4 attached to the rotating shaft 3 of the pulse motor 2. However, there is a deceleration means such as a timing belt between the pulse motor 2 and the cylinder 4. Of course, the moving speed of the piston or rod 14 can be adjusted by providing a. Also,
When it is desired to extend the life of the belt 6 and save maintenance costs, (a) the ratio of the thickness of the belt 6 to the diameter of the cylinder 4 is made as small as possible. (b) Reduce the load acting on the belt 6. (c) Shape of the belt 6 Photoetching is performed to smooth the link lines and punch lines of the long holes 16. It is desirable to consider the following points.

Since this invention has the above configuration, the moving member 13
If the rotation of the pulse motor 2 causes a linear reciprocating motion through the belt 6 wound around the cylinder 4, the force that the belt 6 exerts on the moving member 13 matches the moving direction of the moving member 13. , the torque transmission efficiency is improved compared to the conventional one, and the pulse motor 2 required to operate the liquid dispenser 1 can be made smaller. Further, since there is no need to use expensive screw shafts and nuts as in the conventional case, the manufacturing cost of the liquid dispenser 1 is reduced due to the miniaturization of the pulse motor 2. In addition, since there is no backlash in the threaded part between the screw shaft and the nut as in the conventional case, the amount of movement of the piston or rod 14 can be adjusted accurately and the liquid dispenser 1
accuracy can be improved.

[Brief explanation of the drawing]

Fig. 1 is a front view showing an embodiment of this invention, Fig. 2 is a sectional view taken along A-A', Fig. 3 is a sectional view taken along B-B',
FIG. 4 is a plan view of the belt before winding. 1...Liquid dispenser, 4...Cylinder, 6...Belt, 6a...Wide part, 6b...Narrow width part, 1
1, 12... Guide groove, 13... Moving member, 14...
...Piston or rod, 15...Pump part,
16... Long hole, 20... Leaf spring (biasing means).

Claims (1)

[Claims for Utility Model Registration] 1. A belt partially fixed to the cylindrical surface is wound around the entire circumference so as not to overlap, and both ends of the belt are attached to a movable member that is slidably held along a guide groove. The moving member is attached to the piston or rod enclosed in the pump section, and the piston or rod is caused to reciprocate directly by the rotational movement of the cylinder via a belt wound around it. Liquid dispenser. 2. The belt consists of a wide part having a long hole and a narrow part that can fit into the long hole, and the belt is wound around a cylindrical surface with the narrow part inserted into the long hole of the wide part. Liquid dispenser according to item 1. 3. The liquid dispenser according to claim 1 or 2, wherein the belt is attached to the movable member in a tensioned state by a biasing means. 4. The liquid dispenser according to claim 3, wherein the biasing means is a plate spring attached to one end of the moving member.