JP7469955B2 - Reciprocating Piston Pump - Google Patents

Description

The present invention relates to a reciprocating piston pump.

Conventionally, a reciprocating piston pump in which a piston reciprocates within a cylinder is known, as described in the following Patent Document 1. In the reciprocating piston pump described in Patent Document 1, a piston rod is connected to a crankshaft journaled in a crankcase, and a cylindrical piston packing (piston) that reciprocates within the cylinder is connected to the tip of the piston rod, and the piston packing has an annular packing on its outer periphery that slides against the cylinder.

The piston packing has multiple circumferential through holes that penetrate forward and backward in the axial direction on the inner circumferential side of the packing, and a water intake valve seat is formed at the end facing the axial front. At the tip of the piston rod, a cylindrical water intake valve (valve body) is arranged axially movable forward of the piston packing, and a cylindrical stopper is fixed axially forward of the water intake valve, and a spring is arranged between the stopper and the water intake valve to press the water intake valve so that it seats on the water intake valve seat.

During the intake stroke of the reciprocating piston pump, the piston rod moves axially backward, the intake valve lifts off the intake valve seat against the pressure of the spring, and the liquid from the intake port flows axially forward through the piston packing via the through hole and the gap between the intake valve and the intake valve seat.

When the discharge process begins, the piston rod moves axially forward and the intake valve seats on the intake valve seat, blocking the through hole. The liquid in use, which is axially forward of the piston packing, is then pressurized, and the discharge valve, which is axially forward of the stopper, opens, allowing the liquid in use to be discharged from the discharge port to the outside via the discharge valve.

Japanese Utility Model Application Publication No. 61-181881

In the above reciprocating piston pump, when the intake valve leaves the intake valve seat during the intake stroke, it is desired to ensure a smooth and efficient flow of the used liquid from the intake valve seat through the hole. In addition, it is also desired to reduce the impact when the intake valve sits on the intake valve seat during the discharge stroke. In addition, when the intake valve sits on the intake valve seat during the discharge stroke, the water film is cut due to contact between the flat surfaces, creating a vacuum between the intake valve and the intake valve seat, causing a sticking phenomenon, and when the intake valve leaves the intake valve seat during the intake stroke, pulsation is generated and noise increases.

The present invention was made to solve these problems, and aims to provide a reciprocating piston pump that allows the flow of used liquid from the through hole of the intake valve seat smoothly and efficiently when the intake valve unseats, can reduce the impact when the intake valve is seated, can prevent the generation of pulsation when the intake valve unseats, and can reduce noise.

The reciprocating piston pump (100) according to the present invention comprises a piston rod (7) whose axial rear end is connected to a drive unit (9) and which reciprocates within a cylinder (3); a piston packing (22) which is cylindrical, fitted onto the piston rod (7) and fixed thereto, and which has a plurality of through holes (27) along the circumferential direction that communicate the front and rear in the axial direction; a packing (22a) made of an elastic body held in an annular shape on the outer periphery of the intake valve seat (22b) and which is in sliding contact with the inner periphery of the cylinder (3); and a piston packing (22) which is cylindrical, fitted onto the piston rod (7) so as to be movable in the axial direction, and which has a water intake valve seat (22b) which has a plurality of through holes (27) along the circumferential direction that communicate the front and rear in the axial direction. a reciprocating piston pump (100) equipped with an intake valve (21) located axially forward of intake valve seat (22b) that opens and closes a through hole (27) by lifting and seating on the intake valve seat (22b), and a pressing means (23) that presses the intake valve (21) so that it seats on the intake valve seat (22b), the through holes (27) of the intake valve seat (22b) are spaced apart at equal intervals along the circumferential direction, and a recessed groove (28) recessed axially rearward is provided in an annular shape on the axial front surface of the intake valve seat (22b) so as to connect the axial front ends of the multiple through holes (27).

According to this reciprocating piston pump (100), the intake valve seat (22b) is provided with a plurality of through holes (27) that are spaced apart at equal intervals along the circumferential direction and communicate with the front and rear in the axial direction, and a recessed groove (28) that connects the axial front ends of the plurality of through holes (27) in an annular shape is provided on the axial front surface. Therefore, when the intake valve (21) leaves the intake valve seat (22b), the liquid coming out of the plurality of through holes (27) of the intake valve seat (22b) is temporarily gathered into a ring shape by the recessed groove (28) that connects the through holes (27) in the circumferential direction and hits the intake valve (21), allowing the intake valve (21) to leave the seat with a uniform force, allowing the flow of the liquid to be smooth and efficient. In addition, since the intake valve (21) can be left with a uniform force in this way, the intake valve (21) is also prevented from tilting. In addition, when the intake valve (21) sits on the intake valve seat (22b), the liquid in use stays in the recessed groove (28) that connects the front ends of the through holes (27) of the intake valve seat (22b) in the circumferential direction, so it acts as a cushion and reduces the impact. In addition, the recessed groove (28) provided on the axial front surface of the intake valve seat (22b) prevents the intake valve (21) from breaking the water film when it sits on the intake valve seat (22b), and the vacuum phenomenon between the intake valve (21) and the intake valve seat (22b) is reduced, preventing the sticking phenomenon. As a result, when the intake valve (21) leaves the intake valve seat (22b), pulsation is prevented and noise is reduced.

Here, a specific example of a configuration that effectively achieves the above-mentioned effect is a configuration in which the through hole (27) is an elongated hole that is arc-shaped when viewed in the axial direction. With this configuration, the above-mentioned effect is further enhanced compared to a circular hole.

In this way, the present invention provides a reciprocating piston pump that allows the used liquid to flow smoothly and efficiently from the through hole of the intake valve seat when the intake valve unseats, prevents the intake valve from tilting, reduces the impact when the intake valve is seated, prevents pulsation when the intake valve unseats, and reduces noise.

1 is a vertical cross-sectional view showing a reciprocating piston pump according to an embodiment of the present invention. FIG. 2 is a vertical cross-sectional view showing the piston packing in FIG. 1 . FIG. 2 is a front view of the piston packing in FIG. 1 . 4 is an explanatory diagram of the operation of the main parts of the reciprocating piston pump during the water intake process. FIG. 5A to 5C are diagrams illustrating the operation of main parts of the reciprocating piston pump during a discharge process.

The following describes a preferred embodiment of a reciprocating piston pump according to the present invention with reference to the accompanying drawings. Fig. 1 is a vertical cross-sectional view of a reciprocating piston pump according to an embodiment of the present invention, Fig. 2 is a vertical cross-sectional view of a piston packing, Fig. 3 is a front view of the piston packing, Fig. 4 is an explanatory diagram of the operation of the main parts of the reciprocating piston pump during the water intake process, and Fig. 5 is an explanatory diagram of the operation of the main parts of the reciprocating piston during the discharge process.

The reciprocating piston pump of this embodiment is used in devices such as power sprayers, and various liquids are used as the working liquid for the reciprocating piston pump depending on the application.

As shown in FIG. 1, the reciprocating piston pump 100 generally comprises, from right to left in the figure, a crankcase 1, a water intake manifold 2, a cylinder pipe (cylinder) 3, and a discharge manifold 4, which are connected in this order. Inside the crankcase 1, there are arranged a crankshaft 5 journaled by the crankcase 1, a connecting rod 6 rotatably connected to the crankshaft 5, and a piston pin 8 which rotatably connects the rear end of a piston rod 7 to the connecting rod 6, and the crankshaft 5, connecting rod 6, and piston pin 8, etc., which constitute a drive unit 9 that drives the piston rod 7 to reciprocate. The piston rod 7 is arranged to be able to reciprocate inside the crankcase 1 to the cylinder pipe 3.

Note that Figures 1 and 5 show the piston rod 7 at top dead center during the discharge stroke, in which the piston rod 7 moves axially forward as the crankshaft 5 rotates, and Figure 4 shows the piston rod 7 at bottom dead center during the intake stroke, in which the piston rod 7 moves axially backward.

The crankcase 1 is filled with lubricating oil, and an oil seal 10 is provided at the position where the piston rod 7 passes, to make sliding contact with the piston rod 7 and prevent the lubricating oil in the crankcase 1 from leaking to the intake manifold 2 side. In addition, a seal packing 11 is provided in the intake manifold 2, to make sliding contact with the piston rod 7 and prevent the working fluid on the intake manifold 2 side from leaking to the oil seal 10 side. The intake manifold 2 is provided with an intake port 15 for drawing the working fluid into it.

A discharge valve 17 is provided at the tip of the discharge manifold 4, forward of the cylinder pipe 3, to open and close the flow path and discharge the used liquid to the discharge port 16 when opened. The discharge manifold 4 is also provided with a pressure regulating valve 18 to adjust the pressure of the used liquid being discharged, and an air chamber 19 to cushion the pulsation of the used liquid being discharged.

In addition, a water intake valve mechanism 20 is provided within the cylinder pipe 3. The water intake valve mechanism 20 reciprocates axially together with the piston rod 7. During the water intake process, when the piston rod 7 moves axially backward, the mechanism opens to draw in the used liquid from the water intake port 15 to the discharge valve 17 side. During the discharge process, when the piston rod 7 moves axially forward, the mechanism closes to pressurize the used liquid on the discharge valve 17 side.

As shown in Figures 4 and 5, the water intake valve mechanism 20 mainly comprises a water intake valve 21, a piston packing 22 with a packing 22a and a water intake valve seat 22b that slide against the inner circumferential surface of the cylinder pipe 3, and a spring 23 as a pressing means for pressing the water intake valve 21 so that it seats on the water intake valve seat 22b, as well as a collar 24, a washer 25, and a hexagonal nut 26.

The water intake valve 21 is a disk with a through hole in the center for passing the collar 24 through, and is located axially forward of the piston packing 22. The collar 24 is a cylinder with a through hole in the center for passing the piston rod 7 through, and the outer circumferential surface of the axial rear end is reduced in diameter. The water intake valve 21 is inserted onto this reduced diameter portion 29, allowing it to move axially.

As shown in FIG. 2, the intake valve seat 22b of the piston packing 22 is on which the intake valve 21 is seated and released. It is generally cylindrical with a through hole in the center for the piston rod 7 to pass through, and is located on the axial rear side of the intake valve 21 and collar 24 (see FIG. 4 and FIG. 5). As shown in FIG. 2 and FIG. 3, the intake valve seat 22b has a plurality of through holes 27 that communicate with the front and rear in the axial direction, spaced at equal intervals along the circumferential direction. Here, the through holes 27 are elongated holes that form an arc shape centered on the axis when viewed in the axial direction, and four of them are provided. A recessed groove 28 recessed toward the axial rear is provided in an annular shape on the axial front surface of the intake valve seat 22b, and the axial front end of the through hole 27 is located on the bottom surface (right surface in FIG. 2) of the recessed groove 28.

The packing 22a that constitutes the piston packing 22 is formed into a circular ring shape from an elastic material such as rubber, and is pressed into and held in a circular groove provided on the outer periphery of the water intake valve seat 22b.

As shown in Figures 4 and 5, the piston packing 22, the collar 24 with the water intake valve 21 fitted onto the reduced diameter section 29, and the washer 25 are fitted in this order from the tip side of the piston rod 7, and a spring 23 is interposed between the water intake valve 21 and the washer 25. A hexagonal nut 26 is screwed onto a male screw 30 formed on the tip of the piston rod 7 and tightened, so that the axial rear end face of the water intake valve seat 22b of the piston packing 22 abuts against the enlarged stepped section 31 of the piston rod 7, and the piston packing 22, collar 24, and washer 25 are sandwiched and fixed between the stepped section 31 and the hexagonal nut 26.

In this state, the intake valve 21 is pressed by the spring 23 interposed between the intake valve 21 and the washer 25, and during the discharge process shown in Figures 1 and 5, the intake valve 21 is seated on the intake valve seat 22b, and the through hole 27 and the recessed groove 28 are blocked.

In this type of reciprocating piston pump 100, when the crankshaft 5 is driven to rotate, the piston rod 7 reciprocates within the cylinder pipe 3, repeating the intake stroke (see Figure 4) in which the piston rod moves from the top dead center to the bottom dead center, and the discharge stroke (see Figure 5) in which the piston rod moves from the bottom dead center to the top dead center.

When the discharge stroke is switched to the intake stroke, the piston rod 7 moves axially backward, and as shown in FIG. 4, the intake valve 21 lifts off the intake valve seat 22b against the pressing force of the spring 23, creating a gap between the intake valve 21 and the intake valve seat 22b (the intake valve 21 of the intake valve mechanism 20 opens), the through hole 27 opens, and the used liquid from the intake port 15 passes through the through hole 27 and the recessed groove 28, as shown by the flow of the arrows, and is sucked forward in the axial direction of the piston packing 22.

In this way, when the intake valve 21 leaves the intake valve seat 22b, the used liquid coming out of the multiple through holes 27 of the intake valve seat 22b is temporarily gathered into a ring shape by the recessed grooves 28 that connect the through holes 27 in the circumferential direction and hits the intake valve 21, so the intake valve 21 can be released with a uniform force, allowing the used liquid to flow smoothly and efficiently (improving intake efficiency). In addition, because the intake valve 21 can be released with a uniform force in this way, tilting of the intake valve 21 can also be prevented.

In addition, since the through hole 27 is an elongated hole that is arc-shaped when viewed in the axial direction, the above-mentioned actions and effects can be further enhanced compared to a circular hole.

On the other hand, when the process moves from the intake stroke to the discharge stroke, the piston rod 7 moves forward in the axial direction, and as shown in FIG. 5, the intake valve 21 is seated on the intake valve seat 22b by the pressing force of the spring 23, and the intake valve 21 blocks the through hole 27 and the recessed groove 28 (the intake valve 21 of the intake valve mechanism 20 is closed), and the through hole 27 is closed.

At this time, the liquid in use remains in the recessed groove 28 that circumferentially connects the front ends of the through holes 27 of the water intake valve seat 22b, so it acts as a cushion and can absorb the impact.

In addition, the recessed groove 28 provided on the front surface of the intake valve seat 22b prevents the intake valve 21 from breaking the water film when it is seated on the intake valve seat 22b (reducing surface contact). This reduces the vacuum between the intake valve 21 and the intake valve seat 22b, preventing the intake valve 21 from sticking to the intake valve seat 22b.

In addition, the packing 22a moves forward in synchronous with the axial forward movement of the piston rod 7 while sliding against the inner surface of the cylinder pipe 3, generating water pressure, which presses the intake valve 21 against the intake valve seat 22b with a stronger pressure, improving the sealing performance and reliably blocking the flow of the liquid used.

Then, the used liquid ahead of the piston packing 22 opens the discharge valve 17 as the piston packing 22 moves forward in the axial direction, as shown by the flow of the arrow, and is discharged to the outside from the discharge port 16.

After this, the process switches from the discharge process to the intake process, the piston rod 7 moves axially backward, and as shown in Figure 4, the intake valve 21 leaves the intake valve seat 22b. However, as mentioned above, the recessed groove 28 prevents the intake valve 21 from sticking to the intake valve seat 22b, so pulsation is prevented when the intake valve 21 leaves the intake valve seat 22b, and noise is reduced.

The main actions and advantages of this embodiment have been described above, but this embodiment also provides the following actions and advantages:

In other words, because the flow of the liquid used is in one direction, the water absorption efficiency is high and the reciprocating piston pump itself can be made more energy efficient. In addition, because the flow of the liquid used can be made closer to a straight line, the flow of the liquid used becomes smoother and the water absorption efficiency can be further improved.

In addition, the piston packing 22 moves in sync with the movement of the piston rod 7, preventing pulsation and providing stable performance.

In addition, the structure opens and closes the intake valve 21 by the movable intake valve 21 lifting off and seating on the fixed intake valve seat 22b, and since the weight of the intake valve 21 is lighter than the intake valve seat 22b, the impact force when the intake valve 21 is opened and closed can be reduced, leading to low noise levels. In addition, by forming the intake valve 21 from resin, a significant noise reduction effect can be achieved.

In addition, the intake valve 21 is forcibly opened and closed in accordance with the movement of the piston rod 7, so there is little loss and it can be opened and closed reliably.

In addition, unlike the forced valve piston pump described in JP 2014-224469 A, in which the intake valve abuts against the stopper and the intake valve seat when opening and closing the intake valve, the intake valve 21 only abuts once when it seats on the intake valve seat 22b, which reduces noise.

The present invention has been specifically described above based on the embodiments, but the present invention is not limited to the above embodiments. For example, in the above embodiments, the gasket 22a is made of rubber, which is particularly preferable, but any elastic material will do.

The spring 23 presses the water intake valve 21 to seat it on the water intake valve seat 22b, but a pressing means other than the spring 23 may be used.

In addition, in the above embodiment, the reciprocating piston pump 100 is described as being particularly preferable as an example of application to a power sprayer, but it can also be similarly applied to other reciprocating piston pumps, including reciprocating piston pumps for mist cooling and mist, where cavitation caused by fresh water and noise caused by impact sounds are a concern.

3...cylinder pipe (cylinder), 7...piston rod, 21...water intake valve, 22...piston packing, 22a...packing, 22b...water intake valve seat, 23...spring (pressure means), 27...through hole, 28...recessed groove, 100...reciprocating piston pump.

Claims (1)

A piston rod (7) whose axial rear end side is connected to a drive unit (9) and which reciprocates within a cylinder (3);
a piston packing (22) including a water intake valve seat (22b) having a cylindrical shape, fitted onto the outside of the piston rod (7) and fixed thereto, the water intake valve seat (22b) having a plurality of through holes (27) along a circumferential direction that communicate between the front and rear in the axial direction, and a packing (22a) made of an elastic body that is held in an annular shape on the outer circumferential side of the water intake valve seat (22b) and comes into sliding contact with the inner circumferential surface of the cylinder (3);
a water intake valve (21) having a cylindrical shape, which is externally fitted onto the piston rod (7) so as to be axially movable, which is located on the axial front side of the water intake valve seat (22b) and opens and closes the through hole (27) by lifting off and seating on the water intake valve seat (22b);
a pressing means (23) for pressing the intake valve (21) so that the intake valve (21) is seated on the intake valve seat (22b),
The through holes (27) of the water intake valve seat (22b) are disposed at equal intervals along the circumferential direction,
A groove (28) is provided in an annular shape on the axial front surface of the intake valve seat (22b) so as to be recessed rearward in the axial direction and connect the plurality of through holes (27) ,
The reciprocating piston pump (100) is characterized in that the through hole (27) is an elongated hole having an arc shape when viewed in the axial direction .

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