JPS6231745Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE PRESENT DISCLOSURE The present invention relates to a check valve, and more particularly to a chemically resistant check valve suitable for use in pipetting devices and the like.

Various types of check valves have been developed and used to allow fluid to pass in one direction and prevent it from passing in the other direction. The general characteristics required of a check valve include low flow resistance against flow in one direction and good sealing performance against flow in the other direction. In the case of a check valve, if the flow resistance is large, the pressure difference across the check valve will cause an error in the amount of medicine sucked in, and if the sealing performance is poor, leakage will cause an error in the amount of medicine discharged. This is especially important because it becomes Furthermore, in this case, it should have excellent chemical resistance, easy internal cleaning,
Additional requirements must also be met, such as ensuring that sealing performance is not impaired by clogging with debris. Conventional check valves are known that include a combination of a metal or other rigid valve body or valve seat and a rubber or other flexible valve seat or valve member. This has excellent sealing performance when the valve is closed, but there are problems with chemical resistance and heat resistance (boiling sterilization is often performed to clean the inside). resistance is large. However, it also has the disadvantage that it can easily get caught in dirt. It is also known that the valve body or valve seat is made of glass, but this has the disadvantage of being easily damaged.

The purpose of the present invention is to eliminate these problems. According to the present invention, a valve body and a valve seat have contact surfaces that abut and separate from each other in a casing, and the valve body is pressed toward the valve seat. Provided is a check valve including a spring, characterized in that the valve body is a ceramic ball, the valve seat is made of ceramic, and the abutment surface of the valve seat is previously formed as an annular finished surface. be done. By making the movable valve body a ceramic ball, the weight of the valve body is extremely light.
The resistance when opening the valve is small, and the movement when opening the valve is quick. Ceramic can maintain particularly smooth surface properties for a long period of time, so even if dirt or the like is present in the fluid, it will not get caught on the valve seat or valve body, and can be used for a long period of time.

The abutment surface that abuts against the ball of the valve seat is previously formed as a finished surface that is an annular, narrow, partially concave spherical surface with a radius that is substantially the same as the radius of the ball. In addition, for ball valves, the surface of the ball must be perfectly spherical and smooth so that even if the contact surface of the ball changes due to changes in the position of the ball during operation, the sealing performance will not be impaired. is publicly known. This configuration particularly improves the sealing properties. Further, in order to slightly limit the movement of the ball away from the valve seat, the casing is provided with an abutment piece that can come into contact with the ball on the side opposite to the valve seat. In this way, the opening and closing response of the valve is rapid, and a substantially constant discharge or suction rate can be provided regardless of the magnitude of the pressure differential across the valve.

Conventionally, stainless steel springs have been used in pipette devices for handling chemicals, but they do not have sufficient chemical resistance, and their use is severely limited.
Glass, Teflon, etc. are conceivable materials with high chemical resistance, but they are hardly ever put into practical use. According to a preferred embodiment of the present invention, chemical resistance can be significantly improved by using a coil spring made of platinum-iridium alloy. Although platinum-palladium alloys have almost the same chemical resistance, they tend to sag considerably, making them unsuitable for practical use.

The valve component is housed in a removable casing made of trifluoride resin (commercially available under the trade name Daiflon) or difluoride resin, and a ring made of tetrafluoride resin or hexafluoride resin is used as the gasket ring. By using this, a highly durable check valve with excellent chemical resistance can be obtained.

Embodiments of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, casings 1 and 2 are made of trifluoride resin and are removably engaged with each other by screws.
The outer peripheral surfaces 1a, 2a are provided with appropriate means (not shown) such as notches or polygonal shapes to facilitate removal, installation, and tightening. The ends 1b and 2b are provided with screws for attaching the entire check valve to a suitable device or pipe. Casing member 1
A cylindrical valve seat 3 made of ceramic is press-fitted into the inner end of the valve seat 3, and a valve body 4 made of a ceramic ball is attached to a conical valve seat portion 3a at the inner end of the valve seat 3. It is pressed into contact with a metal coil spring 5. In the figure, 6 is a gasket ring made of tetrafluoride resin.

FIG. 2 shows the details of the valve seat part 3a, and the ball 4
A partially concave spherical surface 3b having a radius that is approximately the same as the radius of the sphere is pre-finished as a narrow abutment surface on the abutment portion where the abutment comes into contact. By forming such a contact surface in advance, the ball makes surface contact with the valve seat rather than a line contact, which significantly improves the sealing performance and provides stable performance over a long period of time.

According to the invention, a device is provided to limit the movement of the ball away from the valve seat to a very small extent. Figures 1 and 3
The figure shows one embodiment of the present invention, in which a sleeve 10 made of trifluoride resin having a through hole 10a with a groove 10b is press-fitted into a housing 2 made of trifluoride resin, as shown in FIG. The edge of the hole 10a limits the amount of movement of the ceramic ball 4 away from the valve seat 3.
In this way, the opening and closing response of the valve is rapid, and a substantially constant discharge or suction rate can be provided regardless of the magnitude of the pressure differential across the valve. For example, this configuration can aspirate a small amount of liquid of less than 500μ,
Errors can be minimized when used as an inlet or outlet valve in an expelling pipetting device. In the preferred embodiment, the ball 4 has a diameter of about 4 mm and its maximum stroke is about 0.1 mm.

The check valve of the present invention is particularly effective as a check valve for a pipette device that dispenses a predetermined amount of chemicals, etc., and has sufficient resistance to various chemicals, sufficient sealing performance, and extremely low flow resistance. casing 1, 2
It is also possible to thoroughly disassemble and clean it by removing it. Furthermore, the combination of a ball valve and a valve seat according to the present invention can be applied to hydraulic devices other than pipetting devices.

FIGS. 4 and 5 each show an alternative embodiment of the invention, and parts corresponding to those in FIGS. 1 and 2 have been provided with the same reference numerals. FIG. 4 shows a discharge valve, with reference numeral 8 indicating a liquid discharge pipe, and 1c and 2c indicating knurling notches provided on the outer circumferential surface. FIG. 5 shows a suction valve, with reference numeral 9 a liquid suction pipe and 7 a restraining ring made of tetrafluoroplastic resin, which constitutes a part of the casing.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a check valve according to the present invention.
FIG. 2 is a partially enlarged sectional view showing the valve and the valve seat. Third
This figure is a front view of the sleeve shown in FIG. 1, and FIGS. 4 and 5 are longitudinal cross-sectional views showing different embodiments. 1, 2: Casing, 3: Valve seat, 3b: Partial spherical surface, 4: Ball, 5: Spring, 6: Gasket ring, 3b: Partial spherical surface, 7: Spring retainer, 1
0: Sleeve.

Claims (1)

[Scope of utility model registration request] In a check valve that includes a valve body and a valve seat that have abutment surfaces that abut and separate from each other in a casing, and a spring that presses the valve body toward the valve seat, the valve body is a ceramic ball, and the valve seat is made of ceramic, and the abutment surface of the valve seat is preformed as a finished surface forming an annular narrow partially concave spherical surface with a radius substantially the same as the radius of the sphere,
Furthermore, the check valve is characterized in that the casing is provided with an abutment piece that can come into contact with the ball on the side opposite to the valve seat in order to limit the movement of the ball away from the valve seat to a minute extent.