JPH0364679A - Low flow rate pump - Google Patents

Abstract

PURPOSE:To always feed a constant low flow rate of gas through simple constitution by a method wherein a flow rate limit body having a gas flow passage formed with a narrow groove is disposed in a closely spaced manner to a gas outlet or a line connected thereto. CONSTITUTION:When a collar 4 is rotated through an output shaft 2 with the aid of a small DC motor 1, a drive shaft 5 performs a pestlelike movement. Since the slope of a drive part 6 is orderly changed through a support part 6, drive parts 11 of diaphragm parts 10 on both side are alternately elevated. As a result, after gas is sucked through a suction hole 6 having a valve 7, it flows through a delivery valve 12 and is discharged through an outlet 15 of a protrusion part 13. In above constitution, a flow rate limit body 20 is disposed in a gas passage at the outlet 15. The low rate limit body 20 is formed such that an outer peripheral surface 22 is engraved to form, for example, a helical groove 21. This constitution always feeds a constant low flow rate of gas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a small air pump, particularly a low flow rate pump with a small flow rate.

[Prior Art] Conventionally, small air pumps have been used in blood pressure monitors and the like. An example of this is the structure shown in FIG.

In this diagram, 1 is a small DC motor and 2 is a motor l.
3 is a case attached to the motor l, 4 is a collar fixed to the output shaft 2, 5 is a drive shaft attached to the collar 4 at an angle, and 6 is a drive body having a cylindrical support part 7. It is attached to the drive shaft 5 by inserting the drive shaft 5 into the support portion 7 . Reference numeral 8 denotes another case which is combined with and fixed on the upper part of case 3, and 9 is a diaphragm body made of soft rubber and has a bell-shaped diaphragm portion IO. A driving part 11 is formed in this diaphragm part 10, and the tip thereof is fixed to a driving body. 12 is the valve body part of the discharge valve; the lid body 1 of the case is attached to the case 8;
4 and is in close contact with the inside of the protrusion 13 extending upward from the center. 15 is an outlet provided on the opposite side of the protrusion 13.

Reference numeral 16 denotes intake holes having valves 17, which are provided in the number of diaphragm portions at positions corresponding to the respective bell-shaped diaphragm portions IO.

In such a small pump, a small DC motor 1 is driven to cause a collar 4 to coaxially move through an output shaft 2, thereby causing a drive shaft 5 to perform a pestle-like motion. Due to the pestle-like movement of the drive shaft 5, the drive unit 6
For example, in the drawing, an upward slope to the right changes direction to an upward slope to the left, and a slope upward to the left changes to an upward slope to the right. As a result, the drive section 11 of the bell-shaped diaphragm section on the right side is lowered, and the drive section 11 of the bell-shaped diaphragm section on the left side is raised. In this way, each diaphragm part is moved up and down by the driving part. The vertical movement of the drive section in each diaphragm section is performed in a phase-shifted state.

[Problems to be Solved by the Invention] In order to further reduce the flow rate in such a small air pump, it is conceivable to reduce the diameter of the diaphragm. Also, it is possible to reduce the size of the straw 7 and the number of rotations of the drive shaft.

All of these conventional methods using small air pumps have the disadvantage that the flow rate becomes unstable, and for example, when used in a blood pressure monitor, the maximum pressure becomes unstable. In other words, the difference between the maximum flow rate and the minimum flow rate is too large, resulting in large fluctuations in the flow rate.

The present invention is a pump for supplying air at an extremely low flow rate, and provides a low flow pump with extremely small fluctuations in flow rate.

[Means for Solving the Problems] The low flow rate pump of the present invention has a flow rate restricting body inserted into the outlet or the gas supply pipe connected to the outlet in a small pump, This flow rate restrictor has a flow path with a small cross-sectional area that communicates from the gas supply side to the gas discharge side, and its outer wall surface is designed to block the passage of gas other than the flow path at the pump outlet or supply side. It is placed in close contact with the inner wall surface of the pipe, and the air discharged from the small pump is discharged and supplied through the flow path of the flow rate restrictor.

Since the low flow rate pump of the present invention has the above-described configuration, the gas discharged by the small pump is limited to an amount smaller than the discharge amount and is supplied through the flow path of the flow rate restricting body. A small flow rate of air defined by this channel is supplied.

[Example] Next, an example of the present invention will be described based on the drawings. FIG. 1 is a sectional view of one embodiment of the low flow pump of the present invention. This embodiment is based on a small pump using a diaphragm shown in FIG. 6, and parts having substantially the same structure as this small pump are indicated by the same reference numerals in the drawings. The pump of this embodiment is provided with a flow rate restrictor 2o in the gas passage of the outlet 15, and this allows the low flow rate of air supply to be reduced to a low flow rate.
This was done under conditions with almost no pressure fluctuations.

The flow rate restrictor used here is as shown in FIG. 2 and has a spiral groove 21. This is inserted into the outlet 15 of the pump by a method such as press fitting, and the outer periphery of the flow restrictor 20, that is, the largest diameter portion 22 corresponding to the threaded portion of the screw is in close contact with the inner wall surface of the outlet. . The gas is then discharged through the spiral 21. That is, the groove 21 of this flow rate restrictor 20, which is the valley of the thread, forms a flow path.

In this embodiment, if the amount of air sent out from the pump chamber is larger than the amount that can pass through the flow path, the flow rate is restricted by this flow rate restrictor, and the larger the flow rate, the more the restricted amount increases, making it difficult to keep the flow rate constant. It can be measured.

In FIG. 1, a flow restrictor 20 is provided at the outlet of the pump and is integrated with the pump. However, the flow rate restrictor 20 may be located at another location other than the location shown in FIG. 1, such as in an air supply pipe.

FIG. 3 and FIG. 4 each show other examples of flow restrictors.

In FIG. 3, a groove 23 is formed parallel to the axis of the cylinder.

This groove 23 constitutes a flow path.

In FIG. 4, (A) is a perspective view, (B) is a side view,
As shown in these figures, a plurality of annular grooves 24 are formed in a cylindrical shape, and another groove 25 is provided to connect these annular grooves.

These flow rate restrictors may be placed at the outlet of the pump, etc., as shown in FIG.

As shown in Figure 5, there is a slot 1 at the outlet 15 of the pump.
5a is provided, and when fitting the gas supply tube etc. to the pump outlet, the tube is press-fitted with the gap closed, so make sure that the flow restrictor does not come out and the outlet part is closed. It is possible to improve the airtightness between the inner wall and the flow restrictor.

The embodiments described above are constructed by using any of the flow restricting bodies of various structures such as the outlet part of a pump using a diaphragm, but the idea of the present invention can be applied to small pumps of other structures. However, the low flow rate pump of the present invention can also be constructed. In other words, by sending the gas sent out from the small pump through a flow path with a small cross-sectional area provided in the flow rate restricting body, the flow rate sent out from the small pump itself is reduced, and changes in flow rate increase/decrease (due to motor rotation, etc.) are softened. I can do it.

[Effects of the Invention] According to the other flow pump of the present invention, it is possible to always supply gas at a constant low flow rate. Furthermore, a low flow rate pump can be constructed with a simple structure in which a flow rate restricting body with an extremely simple structure is provided in the pump itself or in a supply pipe connected to the pump.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the low flow rate pump of the present invention, FIGS. 2 to 4 are diagrams showing various structures of the flow restricting body used in the present invention, and FIG. 5 is the outlet portion of the above embodiment. FIG. 6 is a diagram showing an example of a conventional small-sized pump. 15... Outlet, 20... Flow rate restrictor, 21.23° 24.25... Groove

Claims (1)

[Claims] A flow rate restricting body having a gas flow path formed by a narrow groove is installed in the outlet for sending out gas of a small pump or in the gas supply pipe connected to the outlet on the outer peripheral surface other than the gas flow path. A low flow pump that is placed closely to the inner wall of the pipe to ensure airtightness.