JPH03512B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application) The present invention relates to a hydraulic control device for a reciprocating double-row cylinder type positive displacement pump.

(Prior Art) A conventional pump of this type and a hydraulic control device for this pump are shown in FIG. This pump consists of pump cylinders 1, 1', pump pistons 2, 2', piston rods 3, 3', suction valves 4, 4', working cylinders 5, 5' of the suction valves, and pistons 6, 6', discharge valve 7,
7', an operating cylinder 8, 8' of the discharge valve, its piston 9, 9', and a pump outlet 10.

Operating cylinders 11 and 12 are connected to the pump cylinders 1 and 1', respectively, and operating pistons 13 and 14 are connected to the pump pistons 2 and 2', respectively, via piston rods 3 and 3'.
Pilot valves 1 are installed at both ends of the operating cylinder 11.
5 and 16 are connected to each other, and hydraulic cushions 17 and 18 are connected to both ends of the operating cylinder 12.

The operating valve 19 consists of a second operating valve 19A and a first operating valve 9B, each having a spool 20 and 21. A line 24 connecting the two operating valves is connected to a tank, and a line 25 is connected to a separate hydraulic unit. has been done.

At the position of the spool 20 of the second operating valve 19A in FIG.
, the piston 13 performs a pushing stroke, the oil in the operating cylinder 12 returns to the tank through the pipe 23, and the piston 14 performs a pulling stroke.
At the position of the spool 21 of the first operation valve 19B, the pipe line 26 communicates with the hydraulic unit and the pipe line 27 communicates with the tank, so one pump cylinder 1'
The discharge valve 7' of the other pump cylinder 1 is closed and the suction valve 4' is open, while the discharge valve 7 of the other pump cylinder 1 is open and the suction valve 4 is closed.
The piston 13 of the operation cylinder 11 is the cylinder 11
When reaching the end of the pushing stroke beyond port Q, the pressure in the cylinder on the opposite side is higher than the pressure in the cylinder on the piston rod side, so the pressure oil from port Q pushes the pilot valve 15 and flows into the pipe line 32. Switch by pushing the spool 21 of the one-operation valve 19B. When the first operating valve 19B is switched, the conduits 26 and 27 are respectively connected to the tank and the pump in the opposite way, so that the suction valve and the discharge valve of the pump cylinder are switched to the opposite positions. At the same time, the pressure oil from the pipe 27 passes through the pipe 28 and pushes the spool 20 of the second operating valve 19A to switch, so the pressure oil enters the operating cylinder 12 via the pipe 23 and performs a pushing stroke, and the one-way operation The cylinder 11 is connected to the tank via the line 22 and enters the drawing stroke.

In this hydraulic control device, the flow rate of the pressure oil passing through the first operation valve 19B is adjusted, and the second operation valve 19A
Flow rate regulating valves 30 and 31 are provided in pipe lines 28 and 29 connected to both pilot ports of the second operating valve 19A. However, depending on the adjustment of the flow rate adjustment valves 30 and 31, the switching of the second operating valve 19A is completed and the operating cylinder enters the pushing stroke before the switching of the suction valve and the discharge valve is completed, so that the suction While the valves and discharge valves are being switched, ie, when all the valves are in intermediate positions, pressure is generated by the piston of the pump cylinder entering the push stroke, and there is a risk that the conveyed material will flow backwards. Further, the adjustment of the flow rate regulating valves 30 and 31 requires very delicate adjustment, and there is also a risk that the adjusted positions may be deviated due to vibrations during operation.

OBJECT OF THE INVENTION The object of the invention is to eliminate the above-mentioned drawbacks so that when the pump cylinder has completed its push or pull stroke and is switching over to the next stroke, the suction valve and the discharge valve are in the predetermined position for the next stroke. To provide a hydraulic control device for a reciprocating double-row cylinder type displacement pump, which allows the piston of the pump cylinder to move to the next stroke only after switching to the position, and which does not require delicate adjustments and is easy to maintain. It is to be.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings with regard to an example.

FIG. 1 shows the hydraulic control circuit of the reciprocating double-row cylinder type positive displacement pump according to the present invention when one pump cylinder 1' is in the middle of the pushing stroke and the other pump cylinder 1 is in the middle of the pulling stroke. FIG. 2 shows the same hydraulic control circuit when one pump cylinder 1' has reached the end of its pushing stroke and the other pump cylinder 1 has reached its end of its retracting stroke.

In FIG. 1, the suction valve 4' of the pump cylinder 1' is closed, the discharge valve 7' is open, and the pump cylinder 1'
The spool 21 of the first operation valve 19B is positioned so that the suction valve 4 of the valve 4 is open and the discharge valve 7 is closed, and the spool 21 of the second operation valve 19A is positioned such that the operation cylinder 41 is in the push stroke and the operation cylinder 40 is in the pull stroke. A spool 20 is located there.

Although any pilot pressure generating mechanism may be used to switch the first operating valve 19B at each stroke end position of the operating cylinders 40 and 41, in this embodiment a pilot pressure generating mechanism different from the conventional one is used. . As a pilot pressure generating means, circular protrusions 42a and 42b are formed on both end surfaces of the piston 42 of one operation cylinder 40, and
On the inner surface of both ends of the operation cylinder 40, there are protrusions 42a,
Circular recesses 40a and 40b having the same diameter as 42b are formed. At the end of the pulling stroke of the piston 42,
As shown in FIG. 2, the piston projection 42b fits tightly into the cylinder recess 40a.
A closed annular space 43 is formed between the outer peripheral surface of the cylinder 2b and the inner peripheral surface of the cylinder, and the oil in the annular space 43 is compressed and the pressure increases (theoretically, oil is incompressible, but In reality, it contains air and impurities and is compressed to some extent). The pilot pressure generating section in which this annular space 43 is formed is the pilot valve 44.
The spring that biases the spool 45 is connected via a pipe 46 to the pilot port E on the opposite side, while the pilot port F on the opposite side of the pilot valve 44
is connected to the recess 40b of the operating cylinder 40 by the conduit 47.
is connected to. Furthermore, the input port G of the pilot valve 44 is connected to the second operating valve 19A through the conduit 48.
The output port H is connected to the pilot port I of the first operating valve 19B by a conduit 49.

Further, the other operating cylinder 41 is similarly provided with a pilot pressure generating mechanism. That is,
As pilot pressure generating means, protrusions 50a and 50b are formed on both end surfaces of the piston 50 as before, and recesses 41 are formed on the inner surfaces of both ends of the operating cylinder 41.
a, 41b are formed. As shown by the imaginary line in FIG. 2, a closed annular space 51 is formed by the outer circumferential surface of the protrusion 50b and the inner circumferential surface of the cylinder at the end position of the pulling stroke of the operating cylinder 41.
The pilot pressure generating section that forms the spool 52a of the pilot valve 52 is connected via a pipe 53 to the pilot port E' on the opposite side to the spring that biases the spool 52a of the pilot valve 52. is connected to the recess 41b of the operating cylinder 41 via a conduit 54. Further, the input port G' of the pilot valve 52 is connected to the port B of the second operating valve 19A via the conduit 55, and the output port H' is connected to the pilot port J on the opposite side of the first operating valve 19B.
is connected by a conduit 56.

Furthermore, pilot pressure generating portions forming annular spaces are also formed at the push stroke end positions of both operating cylinders 40 and 41, respectively. Operation cylinder 41
As shown in FIG. 2 at the end position of the pushing stroke, a closed annular space 51' is formed by the protrusion 50a of the piston 50 and the inner peripheral surface of the cylinder, and this annular space 5
In the pilot pressure generating part forming part 1', there is a pipe line 5.
7, the pilot port K of the first pilot valve 58 is connected, and the opposite pilot port L is connected to the recess 41a of the operating cylinder 41 through a conduit 59. The output port M of the first pilot valve 58 is further connected to the pilot port N of the second pilot valve 60 by a conduit 61, while the input port O of the second pilot valve 60 is connected to the port of the second operating valve 19A by a conduit 62. A, and the output port P passes through the conduit 63 to both operating cylinders 40, 4.
It is connected to the pushing stroke end of No. 1. As a result, when pilot pressure is generated and the first and second pilot valves 58 and 60 open, pressure oil can be sent between the pistons 42 and 50 to make up for the lack of oil amount, and the piston 42 and piston 50
Piston 4 on the side that is pushed by the oil between
2 also reliably reaches the end position of the retracting stroke, and the piston 42 in the retracting stroke can be completely moved over the entire stroke. In addition, the other operation cylinder 40
A first pilot valve 58' and a second pilot valve 60' are connected by a similar circuit at the end of the push stroke on the same side of the valve, and can perform the same function when activated. In this case, the input port O' of the second pilot valve 60' is connected to the port B of the second operating valve 19A, and the spool is in the opposite position.

Next, a hydraulic control circuit according to the present invention for opening and closing the suction valves and discharge valves of the pump cylinders 1 and 1' by the operation of the first operation valve 19B will be described.

In FIG. 1 or 2, the first operation valve 19
Port C of B is connected to the suction stroke end side of the suction valve actuation cylinder 64 of the pump cylinder 1 through conduits 27, 79, and to the suction stroke end side of the discharge valve actuation cylinder 82 of the pump cylinder 1' through conduits 27, 80, 81. Connected to the end of the stroke.

Both suction valve operating cylinders 64, 65 are each provided with a pilot pressure generating means that forms a pilot pressure generating section at the end position of its pushing stroke, that is, the piston 66 has a protrusion 66a, as before. 66b, and the inner surfaces of both ends of the cylinder 64 have recesses 64a and 6 that can be tightly fitted with the protrusion.
4b is formed. As shown in FIG. 2, a pilot pressure generating portion forming an annular space 68 generated at the end of the pushing stroke of the piston 66 of the suction valve actuating cylinder 64 is connected to the pilot port Q of the first pilot valve 69 by a conduit 70. The output port R is further connected to a second pilot valve 72 via a conduit 71.
It is connected to the pilot port S of the The input port U of the second pilot 72 is connected to the pipes 73 and 2.
7 and is connected to port C of the first operating valve 19B. The output port V of the second pilot valve 72 is connected to the push stroke end side of the discharge valve actuating cylinder 76 of the pump cylinder 1 via pipes 74, 75, and is connected to the pump cylinder 1 via pipes 74, 77, 78. It is connected to the pushing stroke end side of the suction valve operating cylinder 65, and is further connected to the pilot port W of the second operation valve 19A via a conduit 78.

On the other hand, the port D of the first operation valve 19B is connected to the pipe line 2.
It is connected to the retraction stroke end of the suction valve operating cylinder 65 of the pump cylinder 1' through lines 6 and 83, and further connected to the retraction stroke end of the discharge valve operating cylinder 76 of the pump cylinder 1 via pipes 84 and 85. has been done.

Similarly, a first pilot valve 69' and a second pilot valve 72' are connected to the pilot pressure generating portion at the end of the pushing stroke of the suction valve operating cylinder 65 of the pump cylinder 1'. Second pilot valve 7
The input port U' of the second pilot valve 72' is connected to the port D of the first operating valve 19B via the pipes 73' and 26, and the output port V' of the second pilot valve 72' is connected to the port D of the first operating valve 19B via the pipes 73' and 26. It is connected to the pushing stroke end of the discharge valve operating cylinder 82 of the pump cylinder 1' through the pump cylinder 1', and is connected to the pump cylinder 1 through the pipes 86 and 88.
It is connected to the pushing stroke end of the suction valve actuating cylinder 64, and is further connected to the pilot port X of the second operating valve 19A via a conduit 88 and a conduit 89.

Further, according to the present invention, a cushion mechanism is provided at both stroke end positions of each suction valve and discharge valve operating cylinder. 1, 2 or 3, a closed annular space is formed between the outer circumferential surface of the piston protrusion 66a fitted into the cylinder recess 64a and the inner circumferential surface of the cylinder 64 at the end position of the pushing stroke of the suction valve operating cylinder 64. The pilot pressure generating section forming the pipe 68 is connected to the pipe 90.
A pilot pressure generating section forming an annular space 68' generated at the end of the retraction stroke at the opposite end of the cylinder is connected to a check valve 93 via a conduit 92. There is. Therefore, when the piston 66 moves to the position shown in FIG. 3 and the suction valve 4 is closed, the oil in the annular space 68 formed by the piston protrusion 66a fitting into the cylinder recess 64a is compressed. , flow rate adjustment valve 91
By adjusting the amount of oil that escapes, the cushioning effect can be enhanced. By this,
When closing, the valve body 4 moves rapidly through most of the stroke, and when it approaches the end of the push stroke, it slowly seats at a slow speed, which prevents the generation of noise and loud noise due to sudden metal-to-metal contact as in the past. Premature damage to valves and valve seats due to impact force is eliminated. Also, as shown in the phantom line in FIG. 3, the piston 6 of the suction valve operating cylinder 64
6 reaches the end of the drawing stroke, the closed annular space 68'
is formed, and the escape route for the oil in the space 68' is closed, so that the stroke is completed and the cylinder end surface and the metal surface of the piston no longer come into direct contact.

Now, the operation of the pump cylinder hydraulic control circuit configured as described above will be explained. As shown in FIG. 1, when the pump cylinder 1' is in the push stroke and the pump cylinder 1 is in the pull stroke, and the suction and discharge valves and the first and second operation valves 19B and 19A are in the positions shown in FIG. do. When the piston 50 of one operating cylinder 41 reaches the end position of the pushing stroke (the position shown in FIG. 2), an annular space 5 is formed.
1' and the oil in the pipe 57 are compressed and the pressure increases,
The pilot valve 58 is opened, and the spool of the second pilot valve 60 is pushed open via the pipe line 61, so that the pressure oil (Fig. Valve 6
0, and is further sent between the pistons 50 and 42 via the pipe 63, filling the insufficient amount of oil and ensuring that the piston 42 of the operating cylinder 40 reaches the end position of the pulling stroke as shown in FIG. be able to. When the piston 42 of the operating cylinder 40 reaches the end position of the retracting stroke, the oil in the formed annular space 43 and the pipe 46 is compressed and the pressure rises, causing the pilot valve 4
Push the spool 45 of No. 4 against the spring to open the pilot valve 44. As a result, the second operation valve 19A
Pressure oil from port A passes through conduit 48, pilot valve 44, and conduit 49 to first operation valve 19B.
Enter from port I of the
Switch from the figure to the spool position shown in Figure 2.

When the first operating valve 19B is switched to the spool position shown in FIG.
79 to the piston 6 of the suction valve operating cylinder 64
Press 6 to close the suction valve 4. Furthermore, pressure oil flows through the lines 27, 80, 81 into the discharge valve operating cylinder 82 of the pump cylinder 1', closing the suction valve 7'. Thus, when the suction valve 4 and the discharge valve 7' are closed, the other discharge valve 7 and the suction valve 4' remain closed (the position shown in Fig. 1), so that all the suction and discharge valves are closed. It will be closed. When the suction valve 4 is almost closed, the oil in the annular space 68 is compressed and the pressure increases as described above, opening the first pilot valve 69 and further opening the pipe 71.
Then, the spool of the second pilot valve 72 is pushed open, so that the pressure oil from the pipe 27 passes through the pipe 73, the second pilot valve 72, and then into the pipes 74 and 7.
The discharge valve 7, which had been closed, is opened via the pipe 74, and the suction valve 4' is opened via the pipes 77 and 78. The pressure oil that opened the suction valve 4' further passes from the pipe 78 to the first operating valve 19 via the pipe 78'.
Reach port W of A, push the spool 20 and
Switch from the position shown in the figure to the position shown in Figure 2. When the second operating valve 19A is switched, the pressure oil from its port B pushes the piston 42 of the operating cylinder 40 to enter the pushing stroke, and the piston 50 of the operating cylinder 41 enters the pulling stroke. Thus, the pump 1' sucks in the material to be transported, and the pump cylinder 1 discharges the material.

When the piston 42 of the operating cylinder 40 reaches the end position of the pushing stroke, pilot pressure is similarly generated in the pilot pressure generating section and the first pilot valve 58'
and opens the second pilot valve 60', thereby allowing pressure oil from port B of the second operating valve 19A to flow into the pipe line 6.
2', a second pilot valve 60', and a conduit 63' between the pistons 50 and 42 to ensure that the piston 50 of the operating cylinder 41 reaches the end position of its retracting stroke. As a result, pilot pressure is generated in the pilot pressure generating portion of the annular space 51 formed at the end position of the pulling stroke of the operating cylinder 41, opens the pilot valve 52 via the conduit 53, and opens the second operating valve 19A.
Pressure oil from port B passes through pipe 55, pilot valve 52, and pipe 56, reaches port J of first operating valve 19B, pushes spool 21, and returns from the position shown in Fig. 2 to the position shown in Fig. 1. Switch to As a result, pressure oil from port D of the first operating valve 19B passes through the pipes 26 and 83 to close the suction valve 4', and further passes through the pipes 84 and 85 to close the discharge valve 7. When the suction valve 4' is almost closed, pilot pressure is generated in the pilot pressure generating portion of the suction valve operating cylinder 65, and the first and second pilot valves 69',
72' is activated, and pressure oil from the pump flows through the pipes 26,
The discharge valve 7' is opened via lines 73', 86, and 87, and the suction valve 4 is opened via a pipe 88. Furthermore, pressure oil acts on the spool 20 of the second operation valve 19A from the port X through the pipe line 89, switching it again to the position shown in FIG.
enters the pushing stroke, and the piston 42 of the operating cylinder 40 enters the pulling stroke.

(Effects of the Invention) According to the configuration of the present invention, at the same time as the stroke of each piston of both pump cylinders ends, all remaining open suction valves and discharge valves are closed while leaving the closed suction valves and discharge valves as they are. Then, for the next stroke, the suction and discharge valves, which have remained closed, are opened, and the second operating valve for the operating cylinder is switched to a predetermined position before moving on to the next stroke. When switching between the suction and discharge valves, the risk of the conveyed material flowing backwards due to the intermediate position of the valve is eliminated, and there is no need for extremely delicate adjustments using the flow rate adjustment valve, making maintenance extremely easy. It is.

[Brief explanation of the drawing]

FIG. 1 shows a hydraulic control circuit according to the invention for operating pump cylinders, with one pump cylinder in the pushing stroke and the other in the pulling stroke; FIG. This is a hydraulic control circuit similar to that shown in the figure, but shows a state when one piston reaches the push stroke end position and the other piston reaches the pull stroke end position, and FIG. 3 has a cushion mechanism according to the present invention. FIG. 4, a vertical sectional view of the suction valve operating cylinder, shows a conventional hydraulic control circuit for operating the pump cylinder. 1... One pump cylinder, 1'... Other pump cylinder, 19B... First operation valve, 19A
...Second operating valve, 64, 65...Suction valve operating cylinder, 69, 72, 69', 72'...Another pilot valve, 76, 82...Discharge valve operating cylinder.

Claims (1)

[Scope of Claims] 1. Two operating cylinders each connected in series with two pump cylinders for pressure-feeding a conveyed object and communicated with each other; a pilot valve connected to the stroke end position of the operating cylinder; A first operating valve that is switched by a pilot valve and operates the suction valve and the discharge valve of the pump cylinder, and a second operating valve that operates the operating cylinder.
In a hydraulic control device for a reciprocating double-row cylinder type positive displacement pump, another pilot valve 69, 72, 69', 72' is connected to the push stroke end position of the suction valve operating cylinder 64, 65 of each pump cylinder 1, 1'. Then, one port c connected to the pump side at one switching position (Fig. 2) of the first operating valve 19B is connected to the pulling stroke end of the suction valve cylinder 64 of one pump cylinder 1 and the other port c. It is connected to the retraction stroke end of the discharge valve operating cylinder 82 of the pump cylinder 1', and is further connected to the one port C of the first operating valve 19B via the pilot valve 72 of the suction valve operating cylinder 64 of one pump cylinder. It is connected to the push stroke end of the discharge valve actuation cylinder 76 of one pump cylinder, the push stroke end of the suction valve actuation cylinder 65 of the other pump cylinder, and further to one pilot port W of the second operation valve 19A. Similarly, the other port D connected to the pump side at the other switching position (Fig. 1) of the one-operation valve 19B is connected to the retracting stroke end of the suction valve operating cylinder 65 of the other pump cylinder and the other port D of the one pump cylinder. It is connected to the retract stroke end of the discharge valve actuating cylinder 76, and further connected to the push stroke end of the discharge valve actuating cylinder 82 of the other pump cylinder via the pilot valve 72' of the suction valve actuating cylinder 65 of the other pump cylinder. A hydraulic control device characterized in that the push stroke end of the suction valve operating cylinder 64 of the pump cylinder is connected to the other pilot port X of the second operating valve 19A. 2. The suction valve actuating cylinder has a pilot pressure generating section formed by a pilot pressure generating means at the end of the stroke of the piston, and the pilot valve is connected to the pilot pressure generating section through an input port and is always spring-loaded. A first pilot valve that is closed by a valve body, and a second pilot valve that has a pilot port connected to the output port of the first pilot valve and whose input port and output port are constantly closed by a spring-loaded spool. Consisting of
A hydraulic control device according to claim 1. 3. The pilot pressure generating means has a protrusion having a diameter smaller than the inner diameter of the cylinder protruding from the end face of the piston, and a recess having the same diameter as the protrusion formed on the inner end face of the cylinder opposite to the protrusion, and A pilot pressure generating section is connected to the first pilot valve, and the pilot pressure generating section forms a closed annular space between the inner circumferential surface of the cylinder and the outer circumferential surface of the piston protrusion by tightly fitting the protrusion into the recess at the end of the stroke. Claim 2, wherein the pilot pressure is generated by increasing the pressure of the compressed fluid in the space.
Hydraulic control device as described in section. 4. Two operating cylinders each connected in series with two pump cylinders for pressure-feeding the conveyed material and communicated with each other, a pilot valve connected to the stroke end position of the operating cylinder, and a pilot valve that is switched by the pilot valve. A hydraulic control device for a reciprocating double-row cylinder type positive displacement pump, comprising a first operation valve for operating a suction valve and a discharge valve of a pump cylinder, and a second operation valve for operating the operation cylinder. , another pilot valve 69, 72, 69', 72 is connected to the push stroke end position of the suction valve actuating cylinder 64, 65 of each pump cylinder 1, 1', and one switching position (first position) of the first operating valve 19B is connected. 2), one port C connected to the pump side is connected to the retracting stroke end of the suction valve cylinder 64 of one pump cylinder 1 and the retracting stroke end of the discharge valve operating cylinder 82 of the other pump cylinder 1'. In addition, the one port C of the first operating valve 19B is connected to the push stroke of the discharge valve actuating cylinder 76 of one pump cylinder via the pilot valve 72 of the suction valve actuating cylinder 64 of one pump cylinder. one end of the suction valve actuating cylinder 65 of the other pump cylinder, and further connected to one pilot port W of the second operating valve 19A, and the other switching position of the first operating valve 19B (Fig. 1). ), the other port D connected to the pump side is similarly connected to the pull stroke end of the suction valve cylinder 65 of the other pump cylinder and the pull stroke end of the discharge valve operating cylinder 76 of one pump cylinder, Further, through the pilot valve 72' of the suction valve actuation cylinder 65 of the other pump cylinder, the push stroke end of the discharge valve actuation cylinder 82 of the other pump cylinder and the push stroke end of the suction valve actuation cylinder 64 of one pump cylinder are connected. , in a hydraulic control device connected to the other pilot port a protrusion 66a protruding from the piston end face and having a smaller diameter than the cylinder inner diameter;
A valve cushion mechanism consisting of 66b is provided,
A closed annular space 68, 6 is formed between the inner peripheral surface of the cylinder and the outer peripheral surface of the piston projection by tightly fitting the projection into the recess at the end of the stroke of the piston.
A hydraulic control device characterized in that damping is achieved by compressing the fluid within 8'. 5. Hydraulic control according to claim 4, in which the annular space formed by the fitting of the piston protrusion and the cylinder recess at the end of the piston push stroke of the suction valve or discharge valve operating cylinder is connected to the flow rate regulating valve. Device.