JPS6321370A - Pulsationless metering pump - Google Patents

Abstract

PURPOSE:To permit the proper adjustment of flow rate by constituting a cam mechanism for driving two plungers so that the three-dimensional eccentricity adjustment is permitted so that the stroke length of the plungers can be adjusted at the same time and in symmetrical form. CONSTITUTION:Each one edge of the cross heads 14 and 16 formed integrally with plungers 10 and 12, the hard balls 22 and 24 as cam follower are installed. The cams 26a and 26b in contact with the hard balls 22 and 24 are installed in eccentricity with respect to a turning shaft 28 which crosses at right angles with the cross heads 14 and 16. A three-dimensional structure in symmetrical form which is constituted so that the quantity of eccentricity varies in straight line form in the axial direction of the rotary shaft 28 is provided. Therefore, the quantity of eccentricity of a cam mechanism for each plunger 10, 12 is relatively varied by adjusting the shift in the axial direction of the rotary shaft 28, and the stroke length can be adjusted, and the flow rate can be adjusted simply and smoothly.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a non-pulsating metering pump using a reciprocating plunger pump, which is stabilized by a mechanical configuration without particularly controlling the speed of a drive motor. The present invention relates to an improvement in a pulsation-free metering pump that can obtain pulsation-free characteristics and easily adjust the flow rate.

[Conventional technology]

In general, single-plunger reciprocating pumps have a discharge volume of zero during the suction stroke, and the discharge fluid generates large pulsations. Therefore, two plunger pumps with the same diameter are used to control the reciprocating motion of each plunger. A non-pulsating metering pump has been implemented in which the phase is shifted by 1/2 cycle so that the total displacement of each plunger is always constant. This type of pulsationless metering pump has a special curve that operates in such a way that the total displacement of each plunger is always constant.
By using one or two cams, the total discharge amount due to the pumping operations of the two plungers can theoretically be made pulsating-free. However, in reality, due to the problem of cam machining, it is difficult to completely avoid the pulsation in the combined discharge amount described above, and the flow rate may locally decrease, especially in the combined portion of the two plungers. At the same time, the discharge pressure also decreases and pulsation occurs.

From this perspective, the applicant first connected a drive motor to the cam that drives the two plungers, connected a drive control circuit to the drive motor, and further detected the pressure of the combined discharge amount to determine the pressure fluctuation position. A pulsation-free stationary motor is provided with a circuit for detecting the rotational position of the cam and a circuit 123 for detecting the rotational position of the cam, and is configured to supply output signals obtained from these circuits to the drive control circuit to control the speed of the drive motor. He proposed a pump and filed a patent application (Japanese Patent Application Laid-open No. 70976/1983). The non-pulsating metering pump configured in this way uses the detection signal of the pressure detector to generate the position where the pressure fluctuation of the composite discharge amount occurs, and also generates the actual rotational position signal of the cam, and calculates the position where the pressure fluctuation of the composite discharge amount occurs based on these signals. By appropriately controlling the speed of the drive motor at the time when pressure fluctuations occur, the occurrence of pulsation can be suppressed to an extremely low level compared to a method relying on cam characteristics.

[Problem that the invention seeks to solve]

Generally, in this type of metering pump, by changing the stroke length of the plunger, it is possible to change the volume change amount of the pump chamber and adjust the pump discharge amount. However, as mentioned above, in a pulsation-free pump, in order to prevent pulsation, the sum of the volume changes per medium time in the discharge direction of the two plunger pumps is always constant, and the cam shape is Since the flow rate is constant, the flow rate is constant and cannot be adjusted. Therefore, in order to adjust the flow rate, by changing the rotational speed of the drive motor that moves the cam one rotation, it is possible to realize a change in the flow rate per medium time. Therefore, the conventional pulsationless metering pump described above requires a variable speed motor to adjust the flow rate.

However, in order to achieve pulsation-free stabilization and flow rate adjustment using a variable speed motor, the control circuit becomes complex, and the pulsation-free characteristic may become unstable, especially when adjusting the flow rate. There are disadvantages such as increased equipment costs.

Therefore, an object of the present invention is to provide a cam mechanism that can adjust the stroke length by simultaneously interlocking the plungers of two plunger pumps without using a variable speed morph that requires a complicated control circuit. To provide a pulsation-free metering pump that can easily and smoothly adjust the flow rate while maintaining stable pulsation-free characteristics.

[Means for solving problems]

The pulsation-free metering pump according to the present invention is a pulsation-free metering pump configured to reciprocate two plungers by cam drive to obtain a composite discharge amount by the pump operation of each plunger. A cam mechanism of a similar shape that is displaced in an axial direction perpendicular to the axial direction and whose eccentricity gradually changes with the displacement is provided, and the rotating shaft of this cam mechanism is rotatably and slidably supported in the axial direction. It is characterized in that a part of the shaft is provided with an axial movement adjustment mechanism and is coupled to a rotational drive means.

In the above-mentioned pulsationless metering pump, the cam mechanism is provided on a common rotating shaft, and configured so that the sum of the speeds of the reciprocating motions of the two plungers per unit time is constant when the rotating shaft moves in the axial direction. Can be done.

In addition, the rotation shaft movement adjustment mechanism is configured such that an adjustment screw shaft is connected to one end of the rotation shaft via a joint, and the adjustment screw shaft is rotated with a dial to move the rotation shaft and adjust the flow rate. can do.

Furthermore, the rotational drive means for the rotary shaft can be constructed by coupling a part of the rotary shaft and the drive shaft via a spur gear or a worm wheel, or by directly connecting the drive shaft.

[Effect]

According to the pulsationless metering pump according to the invention, the cam mechanism for controlling the reciprocating motion of the plungers is displaced in an axial direction perpendicular to the axis of each plunger, and the amount of eccentricity gradually changes with the displacement. By adopting an integral structure with similar shapes, when the rotation axis of the cam mechanism is adjusted by moving in the axial direction, the eccentricity of the cam mechanism with respect to each plunger changes in a similar manner, and the stroke length thereof can be adjusted. Therefore, the flow N adjustment can be easily and smoothly achieved.

〔Example〕

Next, embodiments of the pulsationless metering pump according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a mechanical explanatory diagram showing an embodiment of a pulsationless metering pump according to the present invention. In FIG. 1, reference numeral 10
．． Reference numeral 12 indicates two plungers arranged in parallel, and one end of these plungers 10°12 is connected to a crosshead 14.
．． 16 and the cross head 14,1
Ball receivers 18 and 20 are provided at the other end of 6, and these ball receivers 1
Hard ball 22.2 as a cam follower in 8 and 20 respectively
4 is stored and arranged so that it can be transferred freely. Therefore, in this embodiment, the cam 26a comes into contact with the hard balls 22 and 24 as the cam followers.

As shown in the figure, 26b is a similar-shaped ring which is provided eccentrically with respect to the rotating shaft 28 orthogonal to the crosshead 14 and 16, and whose eccentricity changes linearly in the axial direction of the rotating ring 28. It has a three-dimensional structure. In this case, the cams 26a and 26b are integrated with a spur gear 30 between them, and the speed curve (see Fig. 4 (see) and is mounted on the rotating shaft 28 with the phase shifted by 180°. On the other hand, the cam 26a,
26b, a spring 32.34 is provided around the outer periphery of the crosshead 14.16 so that the hard balls 22.24 are always in pressure contact with each other. The rotating shafts 28 are rotatably supported through bearings 36 and 38, respectively, and one end thereof is coupled to an adjusting screw shaft 42 through a joint 40 or the like, and a dial 44 provided on the adjusting screw shaft 42 is connected to the rotating shaft 28. By operating the adjusting screw shaft 42, the rotating shaft 28 is moved by moving the adjusting screw shaft 42 in its axial direction, and the cams 26a, 26b and hard balls 22.2
The structure is such that the contact position with 4 can be changed.

The other ends of the plungers 10 and 12 are inserted into the pump chambers 46 and 48, respectively, via gland seals 50 and 52. In this case, the fluid suction piping that communicates with each pump chamber 46.48 is connected to the common fluid supply source 54 via a check valve, and the fluid discharge piping led out from each pump chamber 46.48 is The piping is configured so that they merge at the junction via check valves.

Furthermore, a spur gear 56 is provided on the rotary drive shaft 54, which is configured to mesh with the spur gear 30 provided integrally with the cams 26a, 26b and to allow movement in the axial direction. Therefore, by coupling and driving the rotation drive shaft 58 with a drive source (not shown) such as an electric motor, the cams 26a and 26b can be eccentrically rotated about the rotation shaft 28.

FIGS. 2 and 3 show the cam 26a described above.

26b shows another embodiment of the drive means for rotating 26b. That is, in FIG. 2, the rotating shaft 28
A worm wheel 60 is connected to the other end, a worm 62 is engaged with the worm wheel 60, and the worm shaft 64 is connected to a drive source.

Further, in FIG. 3, an output shaft 66 of a drive source is directly coaxially coupled to the other end of the rotating shaft 28. By configuring the driving means in this way, the spur gear 30 can be omitted from the cams 26a, 26b, so the configuration is simplified.

Next, the operation of the pulsationless metering pump according to the present invention configured as described above will be explained.

Now, in the state shown in FIG. 1, when the cams 26a526b rotate, these cams 26a.

The crossheads 14, 16, which come into elastic contact with a predetermined position of the ball 26b via the hard ball 22.24, are moved together with the plunger 10.12 in the centrifugal direction and centripetal direction (two-dimensional deviation), respectively, with respect to the rotation axis 28 by 180 degrees. Displaced with a phase difference of °.

At this time, the sum of the speeds of each plunger 10 and 12 in the centrifugal direction (discharge stroke) is set to be always constant (see Fig. 4), and virtually pulsation-free constant discharge is achieved at the confluence of the pump discharge piping. characteristics are obtained.

Therefore, for example, by operating the dial 44, the adjusting screw shaft 4
2 and move the rotating shaft 28 in the axial direction,
The amount of eccentricity changes (three-dimensional deviation) in the portions of force A26a, 26b that the hard balls 22, 24 abut. That is, in the illustrated example, if the cams 26a, 26b move to the right, the amount of eccentricity increases, and if the cams 26a, 26b move to the left, the amount of eccentricity decreases. Incidentally, the change in the discharge flow rate at the confluence point A of the pump discharge piping in this case is as shown in FIG.

〔Effect of the invention〕

As is clear from the embodiments described above, according to the present invention,
In order to reciprocate the two plungers and obtain a composite discharge amount by the pumping operation of each plunger and obtain a pulsation-free constant discharge characteristic, the stroke length of the two plungers is simultaneously controlled by the cam mechanism that drives the plungers with a cam. Moreover, by adopting a configuration that allows three-dimensional eccentricity adjustment for symmetrical adjustment, simply adjusting the axial position of the rotating shaft of this cam mechanism can easily affect the pulsation-free characteristic. Appropriate flow rate adjustment can be performed without any problems.

In particular, according to the non-pulsating metering pump of the present invention, by employing the special cam structure as described above, it is possible to perform highly accurate flow rate adjustment with a simple configuration and easy adjustment operation. Therefore, it is no longer necessary to use an expensive variable speed motor for the electric motor as the drive source for driving the cam mechanism to perform highly accurate speed control as in the past, making this type of pulsationless metering pump system low cost. can be produced.

In addition, in the non-pulsating metering pump according to the present invention, when adjusting the flow rate, the rotation speed of the cam is constant compared to the conventional case where the flow rate per unit time is changed by changing the rotation speed of the cam. Therefore, the pulsation-free characteristic can be always stabilized, and the linearity can be maintained in the flow rate adjustment characteristic.

Although the preferred embodiments of the present invention have been described above, it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a mechanism explanatory diagram showing one embodiment of the pulsationless metering pump according to the present invention, and FIGS. 2 and 3 show different embodiments of the driving means of the cam mechanism of the pulsationless metering pump according to the present invention. FIG. 4 is a waveform diagram showing the discharge flow rate characteristics of the pulsationless metering pump according to the present invention. 10.12. ,, plunger 14.16. ,, Cross to Throat 1B, 20. ,,Ball receiver 22,24
．． ,, Hard ball 26, , Cam 2B, , Rotating shaft 30, , Spur gear 32, 34, , Spring 36, 38. ,,Bearing 40. ,, joint 42), adjustment screw shaft 44. ,, dial 46.
48. ,,Pump room 50.52. ,,Gland seal 54,,Fluid supply source 56. ,, spur gear 581
9. Rotation drive shaft 60. ,,worm wheel 62)
,, Warm 64. ,,worm shaft 66,,,
Output shaft FIG 3 FIG, 4

Claims (4)

[Claims] (1) In a non-pulsating metering pump configured to reciprocate two plungers by cam drive to obtain a combined discharge amount by the pumping operation of each plunger, displacement in an axial direction perpendicular to the axis of each plunger. In addition, a similar-shaped cam mechanism whose eccentricity gradually changes with its displacement is provided, and the rotating shaft of this cam mechanism is rotatably and slidably supported in the axial direction. What is claimed is: 1. A non-pulsation metering pump capable of adjusting flow rate, characterized in that it is provided with a movement adjustment mechanism and is coupled to a rotational drive means. (2) In the pulsation-free metering pump according to claim 1, the cam mechanism is provided on a common rotating shaft, and when the rotating shaft moves in the axial direction, the speed of the reciprocating motion of the two plungers per unit time is A non-pulsating metering pump configured so that the sum of (3) In the pulsation-free metering pump according to claim 1, the movement adjustment mechanism for the rotary shaft connects an adjusting screw shaft to one end of the rotating shaft via a joint, and connects the adjusting screw shaft with a dial. A non-pulsating metering pump configured to adjust the flow rate by moving the axis of rotation as it rotates. (4) In the pulsation-free metering pump according to claim 1, the rotational drive means for the rotary shaft may be configured such that a part of the rotary shaft and the drive shaft are coupled via a spur gear or a worm wheel, or the drive shaft is Pulsation-free metering pump directly connected to.