JPS6390675A - Liquid pump - Google Patents

Abstract

PURPOSE:To provide a liquid pump which has the merits of both a plunger pump form and a double acting boosting pump form, by a method wherein a pressure governing piston and a delivery check valve is situated to a cylinder communicated to a liquid feed source, and return port is formed in a branch pipe. CONSTITUTION:A suction check valve 4 is situated in a branch pipe 2 at the outlet of a check valve 1 communicated to a liquid feed source 17, and is connected to a cylinder 3. A delivery check valve 7 is located to the cylinder 3, a delivery circuit 10 is coupled to the delivery check valve, and a return circuit is formed with a return port 11. Through the working of a pressure governing piston 5 in the cylinder 3,delivery liquid is fed with a pressure, and surplus liquid is returned to the return circuit. This constitution enables provision of the merits of both a plunger pump form and a double acting boosting pump form.

Description

[Detailed Description of the Invention] Generally, low-pressure, large-flow liquid pumps are of the triple plunger type, and a flat valve is often used as the discharge check valve.
For high pressure and low flow rates, a hydraulically driven double-acting pressure increase type is used, and a ball valve is used as the discharge check valve. The advantage of the triple plunger bomber is that there is little variation in discharge pressure, but as the pressure increases, abnormally high pressure occurs in the cylinder when discharge starts, and this abnormal pressure accelerates the wear and tear of the seals and can cause damage to the cylinder. In addition, unless the discharge flow rate of the cylinder and the flow rate used for injection from the nozzle are matched, high pressure liquid will be blown out from the relief valve and the relief valve will not last long. On the other hand, double-acting pressure booster pumps have intermittent motion, so
5 in the cylinder when the piston movement changes (at the start of discharge)! ! Although high pressure does not normally occur, fluctuations in discharge pressure are large.

The present invention provides a high-pressure pump having only the advantages of the above-mentioned drawings, and the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram of a triple plunger pump, and FIG. 2 is an overview of the flat type check valve.

In a triple plunger pump, one of the cylinders is always in the discharge stroke, and the check valves of the other cylinders are pressed against the valve seats by the discharge pressure. The pressed check valve must be pushed up to begin discharging.

In Fig. 2, if the outer diameter D (a~1), inner diameter d (b~b'), and discharge pressure of the check valve I3 are p, then PopDl/
dZ t, the pressure P in the cylinder occurs at the start of discharge 0
For example, if p is 2000 atm, D is 6 mm, and d is 4 mm, P will be 4500 atm, and in this case, during the intake stroke, the check valve 13 will come into contact with the valve seat 14 at 3600 atm due to the discharge pressure of the other cylinders. It becomes pressed down under pressure. If the width of the valve seat is narrowed, P will be lowered, but the contact pressure will be increased, and conversely, if the width of the valve seat is made wider, P will be higher. This problem is not very important when the discharge pressure of the pump is low, but as the pressure increases, it becomes decisively important, causing cylinder damage and causing the high-pressure pump gaskets to not last long. In addition, in FIG. 1, when the drive motor of the 1-land gear 8 is rotating at a constant speed, the cylinder 3 performs fixed-quantity suction and fixed-quantity discharge.
It is difficult to match the discharge amount of the nozzle 15. For this reason, the relief 16 does not last long because high-pressure liquid always blows out from the relief 16.If the rotational speed of the drive motor could be completely controlled, this problem of opening could be solved, but this is practically difficult.

FIG. 3 shows a schematic diagram of the present invention. A branch pipe 2 is provided at the outlet of the original suction check valve 1 communicating with the liquid supply source 17, and a suction check valve 4 is provided in each of the branch pipes 2. Connect to cylinder 3. Further, as described later, a discharge check valve 7 is provided in each cylinder 3, and a discharge circuit 10
Concatenate. Reference numeral 15 indicates a nozzle, and reference numeral 18 indicates a return circuit connecting the return port 11 of each discharge check valve 7 and the branch pipe 2.

FIG. 4 is a schematic diagram of the discharge check valve 7 provided in the cylinder 3. The discharge check valve 7 consists of a large-diameter pressure regulating piston 5, a discharge valve 6 in contact with the pressure regulating piston 5, etc. The pressure regulating piston 5 is pressurized to a required regulating pressure by the pressure regulating valve 19, and the discharge valve Press down on 6.

During the suction stroke of the plunger 8, the suction check valve 4 opens to suck liquid into the cylinder 3, and when the plunger 8 moves to the discharge stroke, the liquid in the cylinder is compressed and the discharge valve 6 is pushed up. This push-up blade and therefore the pressure inside the cylinder are currently controlled by the adjustment pressure. When the discharge valve 6 is pushed up, the discharge port 9 is opened and the discharge circuit 10 is caused to discharge the liquid in the cylinder. The amount of injection from the nozzle 15 shown in FIG.
Furthermore, when the discharge flow rate of the cylinder 3 becomes larger than the discharge flow rate of the discharge circuit 10, the discharge valve 6 is further pushed up to open the return port 11, and the liquid in the cylinder is discharged to the branch pipe 2 via the return circuit 18. Allow reflux. This reflux fluid pressure closes the main suction check valve 1, so that excess fluid is no longer sucked in from the fluid supply source 17. Also, the reflux fluid flows into the cylinder that is on the suction stroke and pushes down the plunger, so it can also be used for energy recovery. Become. When the discharge flow rate of the cylinder 3 decreases, the discharge valve 6 is pushed down by the pressure regulating piston, closing the return port 11, and then the plunger 8
When the valve moves to the suction stroke, the discharge port 9 also closes and the discharge valve 6
is seated on the discharge valve seat 12.

The spring 22 does not need to act when the discharge valve 6 is pushed down, but when it is pushed up, it compresses and pressurizes the pressure regulating piston 5, thereby acting as a discharge valve for each cylinder. ensure its functionality. When the original suction check valve 1 is closed by the recirculating fluid, the amount of suction from the liquid supply source 17 decreases, and the recirculating flow from the discharge valve 6 also decreases and may even disappear, but even in that case, the discharge flow rate of the cylinder 3 The discharge valve 6 also functions as an achievator that absorbs pulsating flow.

As is clear from the above explanation, the liquid pump of the present invention can obtain the required discharge pressure by regulating the pressure of the pressure regulating valve, and even if the pressure becomes high, no abnormal high pressure is generated in the cylinder, so the pump has a long service life. It has advantages such as improved pump performance, and by providing a return circuit, there is no need for a relief valve like in conventional pumps.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional triple plunger pump, FIG. 2 is a flat type check valve, FIG. 3 is a schematic diagram of the present invention, and FIG. 4 is an overview of the discharge check valve 7. ■-Main suction check valve, 2-branch pipe, 3-cylinder, 4-suction check valve, 5-pressure regulating piston, 6-discharge valve 7-discharge check valve,
8-plunger, 9-discharge port, 10-discharge circuit, 11-return port, 12-discharge valve seat, 13-check valve, 14-valve seat, 15-nozzle, 16-relief valve,
17-Liquid supply source, 18-Return circuit, 19-Pressure regulating valve, 20-Check valve, 21-Pressure regulating pressure source, 22-Spring, Fig. 1 Fig. 21

Claims (1)

[Claims] A branch pipe is provided at the outlet of the main suction check valve that communicates with the liquid supply source,
A suction check valve is provided in each of the branch pipes and connected to each cylinder,
Each cylinder is provided with a discharge check valve consisting of a large-diameter pressure regulating piston and a discharge valve in contact with the pressure regulating piston, and during the intake stroke of the plunger in each cylinder, the intake check valve opens and the air flows into the cylinder. The liquid is sucked in, and during the discharge stroke of the plunger, the liquid in the cylinder is compressed, the discharge valve is pushed up against the required adjustment pressure applied to the pressure adjustment piston, and the discharge port is opened to discharge the liquid in the cylinder. When the discharge flow rate of the cylinder becomes larger than the discharge flow rate of the discharge circuit, the discharge valve is further pushed up, the return port communicating with the branch pipe is opened, and the liquid in the cylinder is transferred to the branch pipe. When the discharge flow rate of the cylinder decreases, the discharge valve is pushed down by the pressure regulating piston and the return port is closed.Furthermore, when the plunger moves to the suction stroke, the discharge port is also closed, and the discharge valve is closed to the discharge valve seat. A liquid pump characterized by being seated.