JPH0267471A - Nonpulsating quantitative pump - Google Patents

Abstract

PURPOSE:To make flow regulation easy by interlocking each plunger of double plunger pumps at the same time and installing such a cam mechanism that makes stroke length adjustable, in a device which secures an amount of compound discharge by pumping operation of two plungers. CONSTITUTION:A moving adjusting mechanism 38 of a turning shaft 16 is installed in the upper part of a cam housing 12 supported with the turning shaft 16 with a worm wheel 22 being engaged with a worm 26 on an output shaft 28 of a driving source. This adjusting mechanism consists of an adjusting screw shaft 42 and a joint 48 connecting a dial 46, this adjusting screw shaft 42 and the turning shaft 16. Then, a first cam member 52 and a second cam member 54 are set up in the turning shaft 16 up and down. On the other hand, two plungers 56, 58 are installed in a plunger housing 14 parallelly up and down, and steel balls 64, 66 held by holders 60, 62 at the rear end of the plungers 56, 58 are made contact with each periphery of these cam members 52, 54.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a non-pulsating metering pump using a reciprocating plunger pump, and in particular to a method in which two metering pumps are arranged so that the fluid flows in series. The present invention also relates to an improvement in a pulsation-free metering pump that can obtain stable pulsation-free characteristics through a mechanical configuration without controlling the speed of a drive motor, and can easily adjust the flow rate.

[Conventional technology]

In general, single-plunger reciprocating pumps have a discharge volume of zero during the suction stroke, which causes large pulsations in the discharged fluid. 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 uses one or two cams with special curves that actuate each plunger so that the total displacement volume is constant, and the combined displacement of the two plungers is adjusted. Theoretically, it can be made pulsating-free.

However, in reality, due to problems in cam processing, it is difficult to completely avoid the pulsation in the composite discharge amount described above, and especially in the composite portion of the two plungers, the flow rate decreases locally and 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 composite discharge fluid to determine the position of pressure fluctuation. A non-pulsating metering pump comprising a circuit for detecting the rotational position of the cam and a circuit for detecting the rotational position of the cam, and configured to supply output signals obtained from these circuits to the drive control circuit to control the speed of the drive motor. He proposed and filed a patent application (Japanese Patent Application Laid-Open No. 70976/1983).

In this way, the non-pulsating metering pump configured detects the position where the pressure fluctuation of the composite discharge amount occurs using the detection signal of the pressure detector, and also generates the actual rotational position signal of the cam, and calculates the position 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 system that relies on cam characteristics.

[Problem to be solved by the invention]

Generally, in this type of non-pulsating metering pump, as shown in FIG. 4, two metering pumps 70, 72 are arranged in parallel, and these metering pumps have suction ports 74, 74 and discharge ports 76. 76 are connected by piping so that the fluid flows in parallel. Therefore, in such an arrangement of metering pumps, the piping provided for each pump is collectively connected, so the space occupied by these piping is expanded more than necessary, and the pump installation location is restricted and the piping The complicated structure makes piping work difficult, resulting in high total costs.

Furthermore, the adjustment of the discharge volume in this type of metering pump is
By changing the stroke length of the plunger, the amount of change in volume of the pump chamber was changed.

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, the purpose of the present invention is to arrange two metering pumps one above the other so that the fluid flows in series, and to unify the suction and discharge piping, resulting in a compact overall configuration, while also reducing the complexity of the control circuit. By providing a cam mechanism that can adjust the stroke length by simultaneously interlocking the plungers of two plunger pumps without using a variable speed motor, it is easy to adjust the flow rate while always maintaining stable pulsation-free characteristics. The object of the present invention is to provide a pulsation-free metering pump that can be smoothly achieved.

[Means to solve the problem]

In a non-pulsating metering pump configured to reciprocate two plungers in each pump chamber by cam drive and obtain a composite discharge amount by the pumping operation of each plunger, the fluid sucked in and discharged by the reciprocating movement of each plunger. Connect each pump chamber so that the flow is in series,
A rotary shaft is supported perpendicularly to the axis of each of the plungers so as to be rotatable and slidable in the axial direction. a first cam member that is displaceable and whose eccentricity gradually changes with the amount of displacement; A second cam member is provided to reciprocate the plunger of the discharge side pump chamber so that the combined discharge waveform with the sine wave becomes constant, and further an axial movement adjustment mechanism is provided on a part of the rotating shaft. It is characterized in that it is provided and coupled with a rotational drive means.

In this case, it is preferable that the first and second cam members have a substantially conical shape, and the contact portions of the plunger that contact the first and second cam members, respectively, make point contact with each other. .

Further, the movement adjustment mechanism for the rotating shaft is configured such that an adjusting screw shaft is connected to one end of the rotation through a joint, and the adjusting screw shaft is moved in the axial direction by rotation of a dial to adjust the flow rate. It may be configured.

Further, 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 directly coupled to the drive shaft.

[For production]

According to the pulsationless metering pump according to the present invention, the pair of cam members are rotated via the rotation shaft by driving the rotation drive means. Due to the rotation of the cam member, each plunger is displaced in a centrifugal direction and a centripetal direction (two-dimensional displacement) with respect to the rotating shaft with a phase difference of 180° in a cross section perpendicular to the axis. In this case, the pump chambers are arranged so that the fluid sucked in and discharged by the reciprocating motion of the plunger is connected in series, and each plunger is reciprocated by a combination of a pair of cam curves and a check valve. The composite waveform of the discharge waveform of the plunger can be made substantially constant. Furthermore, by adjusting the rotational shaft by moving it in the axial direction, the amount of radial displacement of the cam relative to each plunger will gradually change, and the stroke length will be adjusted, making three-dimensional eccentric adjustment possible and simplifying flow rate adjustment. and can be achieved smoothly.

〔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 sectional view of essential parts showing an embodiment of a pulsationless metering pump according to the present invention. In FIG. 1, reference numeral 10 denotes a pump housing consisting of a cam housing 12 and a plunger housing 14. A rotating shaft 16 is rotatably supported in the cam housing 12 by bearings 18 and 20 in a vertical direction. Further, a worm wheel 22 is rotatably supported by a bearing 20 on the lower side of the rotating shaft 16, and one end (lower side in the figure) of the rotating shaft 16 is slidable in the axial direction via a key 24 on the worm wheel 22. is inserted into. Further, a worm 26 fixed to an output shaft 28 of a drive source (not shown), such as a motor, through a key 30 is engaged with the worm wheel 22, so that the rotation shaft 16
is rotationally driven at a predetermined reduction ratio. On the other hand, the rotating shaft 1
A boss 32 fits into the inner ring of the bearing 18 that supports the other end (upper side in the figure) of the bearing 6, and a rotary shaft is inserted into the boss 32 via a key 34 so as to be slidable in the axial direction. ing.

A small housing 3 is provided on the upper part of the cam housing 12.
6 is placed thereon, and this housing 36 is provided with a movement adjustment mechanism 38 for the rotating shaft 16. That is, this movement adjustment mechanism 38 includes an adjustment screw shaft 42 that is screwed into a through screw hole 40 of the housing 36, and a dial 4 that is attached to an end of a small diameter shaft 44 that extends from one end of this adjustment screw shaft 42.
6, and a joint 48 at the other end (lower side in the figure) of the adjusting screw shaft 42, which connects the adjusting screw shaft 42 and the rotary shaft 16 so as to be rotatable with each other on the same axis. Further, a scale is engraved on the outer periphery of one end of the dial 46, and a scale is also engraved on the side of the cylindrical case 50 attached to the upper part of the housing 36, and the combination of these scales determines the axis of the rotating shaft 16. The amount of directional movement can be read or set.

Further, a pair of cam members consisting of a first cam member 52 and a second cam member 54 are disposed above and below the rotating shaft 16.

On the other hand, inside the plunger housing 14 is the rotating shaft 16.
Two plungers 56.58 perpendicular to the first and second cams are provided vertically and parallel to each other, and are rotatably attached to a holder 6062 at the rear end (left side in the figure) of the plungers 56.58. The held steel balls 64 and 66 are in contact with the outer peripheries of the first and second cam members, respectively.

Furthermore, the steel balls 64, 66 are urged against the first and second cam members 52, 54 by the action of coil springs 68, 70.

Further, on the right side of the plunger housing 14, a first pump gauging 74 in which a first pump chamber 72 is formed and a second pump casing 78 in which a second pump chamber 76 is formed are arranged vertically. It is arranged. The tip of the plunger 56.58 (on the right side in the figure) is inserted into each of the pump chambers 72.76 so as to be movable forward and backward, and the inserted portion is sealed by a seal portion 80.82. A suction port 84 is provided in the second pump gauging 78 provided on the lower right side of the plunger housing, and a check valve 86 is installed between the suction port 84 and the second pump chamber 76 .

Further, the discharge port of the second pump casing 78 and the suction port of the first pump casing 74 provided above the second pump casing 78 are connected to each other via a check valve 88, and A discharge port 90 is provided. In this case, it is not necessary to provide the discharge port 90 with a check valve, but it is not prohibited to provide it especially for the purpose of preventing backflow or rectifying the flow.

In this way, the metering pumps that perform a pumping action by the reciprocating motion of the plungers are arranged so that their fluid flows in series with the right side surface of the plunger housing via the respective check valves.

Next, the first metering pump 92 and the second metering pump 92 are arranged vertically.
The operation of the metering pump 94 will be explained.

The plunger 58, whose one end is inserted into the second pump chamber 76 provided on the lower side, moves backward by the amount of displacement caused by the rotation of the second cam member 54, and this movement causes the fluid to flow through the check valve 86. and flows into the second pump chamber 76 .

Further, as the second cam member 54 rotates together with the rotating shaft 16, the second cam member 54 is displaced in the radial direction, causing the plunger 58 to advance. As a result, the second pump chamber 76
The liquid compressed within passes through the check valve 88 and flows into the first pump chamber 72 . In this case, at the same time, the upper plunger 5 is inserted into the first pump chamber 72 so as to be freely retractable.
6, the first cam member 52 formed with a phase difference of 180° from the second cam member 54 starts a reciprocating motion relative to the lower plunger 58, that is, a backward movement. Therefore, the liquid in the second pump chamber 76 flows into the first pump chamber 72. When the first cam member 52 further rotates, the plunger 56 enters the forward motion again, and the liquid in the first pump chamber 72 is discharged from the discharge port 90, forming a serial fluid flow.

Traditionally, the suction and discharge strokes are performed simultaneously by moving each plunger relative to each other, thereby canceling out the peaks and valleys (pulses) that occur in each flow waveform, and making the combined discharge amount constant. Parallel type pulsation-free pumps that prevent pulsation are known. however,
In order to completely avoid pulsations in the combined discharge amount, the cam shape has to be complicated, which has been considered difficult.

Therefore, the present invention solves the above problem at once by arranging the first and second metering pumps so that their flows are in series.

That is, the problem can be solved by a combination of the first and second cam members 52,54 that provide the motion of each plunger 56,58 to obtain the flow waveforms shown in FIGS. 2(a), 2(b), and 2c, respectively. can. However, the second cam member 54 is a conical cam whose eccentric shaft is displaced with respect to the rotating shaft so that the cross section perpendicular to the rotating shaft 16 becomes an eccentric circular cam, so that the movement of the plunger 58 is controlled as shown in FIG. It can be constructed so that the sine wave shown in c) is drawn. As a result, the plunger 56 changes the shape of the cross section perpendicular to the axis of the second cam member so that the combined discharge flow rate waveform discharged from the first pump chamber 72 becomes the waveform shown in FIG. 2(a). (b)
It is possible to avoid pulsation by combining the first and second cam members. In this case, like the second cam member 54, the first cam member 52 is a special approximately conical cam whose eccentric shaft is displaced with respect to the rotating shaft 16. That is, the first and second cam members are formed so that the amount of displacement in the axial direction and the amount of eccentricity in the axial cross section are proportional to each other. Therefore, each cam member 5
By moving the rotary shaft 16 having a diameter of 2.54 in the axial direction by the action of the adjusting screw shaft 42 through the rotation of the dial 46, the stroke length of each plunger 56° 58 is proportionally displaced in proportion to the amount of displacement. The discharge amount can be adjusted as appropriate.

However, if the discharge rate of the second pump is 91 and the discharge rate of the first pump is 92, then when the maximum discharge rate is A,
If the rotation angle of the rotating shaft 16 is θ, then q, =A Sinθ (1) and where 0≦θ≦π =A/π (3) where π
≦θ≦2π.

It goes without saying that when the first and second cams each have a special shape, the flow rate waveform does not necessarily have a sine wave shape.

That is, to explain this based on the explanation of the flow rate waveform when using a specially shaped cam shown in FIG. The amount of axial displacement of the shaft 16, θ is the rotation angle of the rotary shaft 16), and θ is the point at which f(θ)=0 (when switching between discharge and suction). , θ1, then Bo is obtained. Here, if the flow rate waveform of the first metering pump 92 is k·9(θ), θ. In the range ≦θ≦θ. Also, if the point where q(θ)-〇 is θ2°θ3, then in the first metering pump 92, (4) 2~
If a flow rate waveform that satisfies the relationship in equation (8) can be obtained, there is no need for a sinusoidal waveform.

〔Effect of the invention〕

As is clear from the embodiments described above, according to the non-pulsating metering pump according to the present invention, the pumps are connected and arranged so that the fluids sucked in and discharged by the reciprocating motion of each plunger are in series. This eliminates the need for suction and discharge piping required for conventional parallel-type non-pulsation metering pumps, reduces the area occupied by the pump, and saves space.

Furthermore, a first cam member is provided on the rotating shaft so as to be displaced in the axial direction so as to give a sinusoidal motion to the reciprocating motion of the plunger in the suction side pump chamber, and the amount of eccentricity gradually changes with the amount of displacement; The discharge side pump chamber is disposed on the same axis as the cam member, is displaced in the same axial direction as this axis, and is displaced in the radial direction relative to the first cam member, so that the composite discharge waveform with the sine wave is constant. The stroke length of the two plungers can be adjusted simultaneously and symmetrically by providing a cam member that reciprocates the plungers, and further providing an axial movement adjustment 81 on a part of the rotating shaft. This makes it possible to adjust the amount of eccentricity in three dimensions, and by simply adjusting the axial displacement, it is possible to easily and appropriately adjust the flow rate without affecting the pulsation-free characteristics.

In addition, the cam shape of the suction side pump is a simple conical shape, and it is sufficient to use a specially shaped cam only for the discharge side pump. Therefore, it is easy to manufacture, the manufacturing cost is low, and the configuration is simple and the adjustment operation is also easy. This allows highly accurate flow rate adjustment. However, unlike in the past, speed control using an expensive variable speed motor for the electric motor as a drive source for driving the cam mechanism is no longer necessary, and the total cost can be reduced.

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 sectional view of essential parts of a pulsationless metering pump according to the present invention,
FIG. 2 shows a discharge amount waveform diagram of the pulsationless metering pump according to the present invention, FIG. 2(a) is a composite waveform diagram, FIG. 2(b) is a flow rate waveform diagram of the first metering pump, and FIG. Figure (C) is a flow rate waveform diagram of the second metering pump, Figure 3 is an explanatory diagram of the flow rate waveform in the case of a specially shaped cam, and Figure 4 is an overall perspective view of a conventional non-pulsation metering pump. 10...Pump housing 12...Cam housing 14...Plunger housing 16...Rotating shaft 18.20...Bearing 22.
...Worm wheel 24.30.34...Key 26...Worm 2
8...Output shaft 36...Housing 40...Threaded through hole 44...Small diameter shaft 48...Joint 52...First cam member 54...Second cam member 56, 58 Plungers 60, 62... Holders 68, 70... Coil spring 72... First pump chamber 74... First pump casing 76... Second pump chamber 78... Second pump gauging 80, 82... Seal portion 84... Suction port 86.8
8... Check valve 90... Discharge port 92... First metering pump 94... Second metering pump 100.102... Metering pump 104... Suction port 106... Discharge Exit 32...
・Boss 38...Movement adjustment mechanism 42...Adjustment screw shaft 46...Dial 50...Cylindrical case 64, 66...Steel ball FIG. FIG. (a) FIG.

Claims (4)

[Claims] (1) In a non-pulsating metering pump configured to reciprocate two plungers in each pump chamber by cam drive and obtain a composite discharge amount by the pumping operation of each plunger, suction and discharge are performed by the reciprocating movement of each plunger. The pump chambers are connected and arranged so that the fluid flows in series, and a rotating shaft is supported perpendicularly to the axis of each plunger so as to be rotatable and slidable in the axial direction. a first cam member disposed on the shaft so as to be displaced in the axial direction so as to impart sinusoidal motion to the reciprocating motion of the plunger in the suction side pump chamber, and whose eccentricity gradually changes with the amount of displacement; and this first cam member. a second cam that is displaced in the same axial direction as the first cam member and radially displaced relative to the first cam member, and reciprocates the plunger in the discharge side pump chamber so that a composite discharge waveform with the sine wave is constant; A pulsationless metering pump characterized in that a member is provided, and further an axial movement adjustment mechanism is provided on a part of the rotating shaft, and a rotational drive means is coupled. (2) the first and second cam members are approximately conical;
2. The pulsationless metering pump according to claim 1, wherein the contact portions of the plunger that respectively contact the first and second cam members are configured to make point contact with each other. (3) The rotation shaft movement adjustment mechanism connects an adjustment screw shaft to one end of the rotation shaft via a joint, and adjusts the flow rate by moving the adjustment screw shaft in the axial direction by rotating a dial. The pulsationless metering pump according to claim 1, which is configured to perform the following. (4) The non-pulsation metering pump according to claim 1, wherein the rotational drive means for the rotary shaft is formed by coupling a part of the rotary shaft and the drive shaft via a spur gear or a worm wheel, or directly connecting the drive shaft. .