JPS6056278B2 - Piston pump hydraulic actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a piston for a concrete pump, etc., which reciprocates a pump piston in a pump cylinder by operating a pump-driving hydraulic cylinder, and sucks in and pressurizes a fluid such as concrete. This invention relates to a hydraulic actuator in a pump.

Generally, the hydraulic actuation device of such a piston pump is
By switching the pump drive switching valve, high pressure hydraulic oil generated from a high pressure oil source such as a hydraulic pump is supplied to the pump drive hydraulic cylinder by alternating the flow direction,
A drive piston that slides within a hydraulic cylinder is reciprocated.

As the drive piston reciprocates, the pump piston is reciprocated to perform a pumping action. By the way, in concrete pumps that handle heavy fluids such as concrete, if the pump is temporarily stopped while pumping concrete, the hydraulic oil in the hydraulic cylinder will flow back toward the oil tank due to the weight of the concrete being pumped. Then, there is a risk that the pump piston will reverse and collide with the end wall of the pump cylinder, causing damage, and furthermore, there is a risk that the hydraulic equipment, piping system, etc. will be damaged.

In order to eliminate this inconvenience, it is necessary to shut off all ports of the pump drive switching valve connected to the hydraulic cylinder while the pump is temporarily stopped. In addition, in conventional piston pumps, the switching valve for driving the pump was generally configured as a pilot-operated type, and it was automatically switched in relation to the operation of the hydraulic cylinder, so the piston pump was restarted when it was temporarily stopped. In order to generate a predetermined pilot oil pressure, that is, a pilot oil pressure that switches the switching valve from the neutral position to the operating position, it is necessary to shut off all ports of the pump drive switching valve that are connected to the hydraulic pump. Ta.

Due to these requirements, conventional piston pumps of this type have a switching valve for driving the pump as described in Japanese Patent Application Laid-open No. 53-10.
As shown in Publication No. 3205, it has become common to use a three-position switching valve that shuts off all boats in the neutral position. However, when such a three-position switching valve is used as a pump drive switching valve, each time the switching valve is operated to switch the flow direction and supply high-pressure hydraulic fluid from the hydraulic pump to the pump drive hydraulic cylinder. In this case, the flow of hydraulic oil is always interrupted at the neutral position. When such a sudden circuit closure occurs,
Pressure in the circuit increases momentarily. In other words, the surge pressure increases. As a result, problems such as noise and damage to the hydraulic pump, other hydraulic equipment, and piping systems have occurred. Therefore, the present invention aims to solve this problem, and when the pump drive switching valve is in the neutral position, a high-pressure hydraulic power source such as a hydraulic pump is communicated with the oil tank through the throttle hole, This prevents the circuit from the hydraulic source to the oil tank from being suddenly closed during the switching operation of the switching valve, reduces surge pressure, reduces noise generation, and increases durability. It is an object of the present invention to provide a hydraulic actuation device for a piston pump in which a pilot hydraulic pressure is reliably generated from a hydraulic source and a transition from a stopped state to a driven state is smoothly performed.

In order to achieve the above object, the present invention provides a pump cylinder on which a pump piston slides; a pump driving hydraulic pressure connected to the pump cylinder and on which a driving piston integrally connected with the pump piston slides; a cylinder; a bi-instrumentally operated pump drive switching valve that switches the flow direction of hydraulic oil supplied to the hydraulic cylinder from a high-pressure hydraulic source to reciprocate the driving piston; and a pilot hydraulic pressure from the high-pressure hydraulic source. and a control valve that alternately switches the switching valve in relation to the operation of the hydraulic cylinder; , and a valve housing having boats each connected to an oil tank, and a spool that slides within the valve housing and shuts off all boats connected to the hydraulic cylinder when the switching valve is in a neutral position; This spool has
When the switching valve is in a neutral position, a throttle hole is provided that allows communication between a boat connected to the high-pressure hydraulic power source and a boat connected to the oil tank. Hereinafter, one embodiment of the present invention will be described according to the drawings. In FIG. 1, a pair of pump cylinders 1, 1'' are arranged in parallel with each other.
First and second pump driving hydraulic cylinders 2, 2'' are connected to the base end of the pump.

Pump pistons 3, 3'' that slide into each pump cylinder 1, 1'' and drive pistons 4, 4'' that slide into each hydraulic cylinder 2, 2'' are connecting rods 5, 5'', respectively.
The drive piston 4,4″
The inside of each hydraulic cylinder 2, 2'' is located at the base end A, a'', respectively.
and a tip chamber B, b''. At the tip of each hydraulic cylinder 2, 2'', there is a pair of control valves 6, which are activated when the drive piston 4, 4'' reaches the tip. 6″ is provided.

Each control valve 6, 6'' is a pilot-operated check valve that opens and closes an inflow boat 7, 7'' and an outflow boat 8, 8'', respectively, and its valve rod 9, 9'' is connected to a hydraulic cylinder 2, 2''. The control valves 6, 6'' project into the tip chambers B, b'' of the
When the drive piston 4, 4'' comes into contact with this valve rod 9, 9'', it opens, and when the drive piston 4, 4'' moves away, it closes.The tip of each pump cylinder 1, 1'' A common valve chamber 10 is provided across them, and a discharge pipe 11 is connected to the central portion of this valve chamber 10.

A valve 12 is slidably fitted into the valve chamber 10, and the valve 12 forms a base chamber c and a tip chamber d. By alternately supplying hydraulic oil to the base chamber c and the tip chamber d, the valve 12 operates reciprocally, and the pump cylinder 1 and the discharge pipe 11, or the pump cylinder 1'' and the discharge pipe 11 are alternately connected. In addition, valves 12 are provided at both ends of the valve chamber 10.
A pilot-operated check valve 13 that opens when the
, 14 are provided, respectively. A high-pressure oil passage 15 connected to the discharge side of the hydraulic pump P, which is a high-pressure oil source, is branched into branch high-pressure oil passages 16 and 17. One of the branch high-pressure oil passages 16 is a pump drive having a pilot-operated 3-position switching valve. The other branch high-pressure oil passage 17 communicates with a valve operation switching valve 19 which is also a pilot-operated two-position switching valve.

Further, the hydraulic oil discharged from these switching valves 18 and 19 is returned to the oil tank T via a return oil line 20. Other oil passages 21 and 22 coming out from the other side of the pump drive switching valve 18 communicate with the front chambers B and b'' of the hydraulic cylinders 2 and 2'', respectively, and also communicate with the front chambers B and b'' of the hydraulic cylinders 2 and 2'', respectively. Other oil passages 23 and 24 coming out from the other side communicate with the base chamber c and the tip chamber d of the valve chamber 10, respectively.
The base chambers A, a'' of the respective hydraulic cylinders 2, 2'' are communicated with each other by a connecting oil passage 25, and hydraulic oil is introduced into the tip chamber b of the hydraulic cylinder 2, causing the drive piston 4 to move toward the base side. At this time, the hydraulic oil in the base chamber a is connected to the connecting oil passage 25.
It flows into the base chamber a'' of the hydraulic cylinder 2'', and presses and moves the drive piston 4'' toward the tip side.

The hydraulic oil in the tip chamber b'' of the hydraulic cylinder 2'' is
It is discharged through the oil passage 22. Similarly, when the drive piston 4'' moves toward the base side, the hydraulic oil in the base chamber a'' is sent to the base chamber a through the connecting oil passage 25, and the drive piston 4 is pushed toward the tip side. Then, the hydraulic oil in the tip chamber b is discharged through the oil passage 21. Near the pump driving switching valve 18 and valve operating switching valve 19, first and second solenoid valves 28 and 29 for switching and operating these are respectively arranged. Pilot oil pressure is applied to the left and right sides of the pump drive switching valve 18 by pilot oil passages 30 and 31 connected to the two boats, and pilot oil passages 32 and 33 connected to the two boats on one side of the second solenoid valve 29 are applied. Switch valve 1 for valve operation
Pilot hydraulic pressure is applied to the left and right sides of 9.

These first and second solenoid valves 28 and 29 are three-position switching valves that are in the right position or normal rotation position and in the left position or reverse rotation position in the figure. On the other hand, the two boats on the other side of the first solenoid valve 28 are connected to the inflow boats of the check valves 13 and 14 provided at both ends of the valve chamber 10 via pilot oil passages 34 and 35, respectively. ing.

The outflow boats of the check valves 13 and 14 are communicated with the oil passages 24 and 23 through pilot oil passages 36 and 37, respectively. Further, the two boats on the other side of the second solenoid valve 29 are connected to the inflow boats 7, 7'' of the control valves 6, 6'' via pilot oil passages 38, 39. The outflow boat 8 of this control valve 6 is connected to the pilot oil path 40.
The outflow boat 8'' of the control valve 6'' is communicated with the tip chamber b'' of the first hydraulic cylinder 2 through the pilot oil passage 41. A relief valve 42 is provided between the high pressure oil passage 15 and the oil tank T.
This relief valve 42 causes the oil passage 1 to close when the oil pressure in the high pressure oil passage 15 becomes higher than the set pressure.
The hydraulic oil in the pump 5 is discharged to maintain the oil pressure below a set value.

Next, the specific structure of the pump drive switching valve 18 will be explained. As shown in FIG. . The valve housing 43 has oil passages 21 and 22 on one side thereof.
Boats A and B are connected to the front chambers B and b'' of the hydraulic cylinders 2 and 2'' through the oil passages 15 and 16, respectively. C and a boat D connected to the oil tank T via the return oil path 20. Grooves 45, 46, 47, and 48 are formed on the inner surface of the valve housing 43 and are connected to the boats A, B, C, and D, respectively. Pilot oil chambers 49 and 50 are defined. The pilot oil chambers 49 and 50 communicate with pilot oil passages 30 and 31, respectively. On the other hand, the spool 44 has four large-diameter parts 51, 52, 53, and 54 that are in sliding contact with the inner surface of the valve housing 43, and three large diameter parts that form an oil passage between these and the inner surface of the valve housing 43. Three small diameter portions 55, 56, and 57 are provided.
Further, inside the spool 44, a communication hole 58 that allows hydraulic oil to flow between the small diameter portions 55 and 57, and a throttle hole 59 that allows communication between the outer peripheral surfaces of the large diameter portions 52 and 53 are bored.
This throttle hole 59 has a small diameter and a large flow resistance, and when hydraulic oil flows through this throttle free hole 59, its back pressure is increased to a predetermined pressure. When the spool 44 is in the center position as shown in FIG. The oil is discharged from the boat D through the tank and flows back into the oil tank T.

At this time, as described above, the flow of the hydraulic oil is restricted by the throttle hole 59, so the oil pressure in the oil passages 15 and 16 increases. Further, at this time, the groove 45 connected to the boat A and the small diameter portion 55 of the spool 44 facing thereto are closed by the large diameter portions 51 and 52, and the small diameter portion 57 communicating with the small diameter portion 55 is also closed by the large diameter portion 55.
3 and 54, the oil passage 21 connected to boat A is blocked. Similarly, groove 46 connected to boat B
Since the small diameter portion 56 facing this is closed by the large diameter portions 52 and 53, the oil passage 22 connected to the boat B is also blocked. That is, when the switching valve 18 is in the neutral position, boats C and D are communicated through the throttle hole 59, and both boats A and B are cut off. Next, when high pressure hydraulic oil is sent to the left pilot oil chamber 49, the spool 44 is pushed to the right and moves to the state shown in FIG. 2b.

At this time, the switching valve 18 will be switched to the left position. In this position, boat C communicates with groove 45 and boat A through groove 47 and small diameter section 55, and boat D communicates with groove 48 through groove 45 and boat A.
, communicates with the groove 46 and the boat B through the small diameter portion 56.
Therefore, high pressure hydraulic oil is sent from boat C to boat A, and return hydraulic oil is returned from boat B to boat D. Further, when high pressure hydraulic oil is introduced into the pilot oil chamber 50 on the right side, the spool 44 moves to the left side, and as shown in FIG.
The state will be as follows.

At this time, the switching valve 18 has been switched to the right position. At this position, J and boat C are connected to groove 47 and small diameter section 5.
6 through the groove 46 and the boat B, and the boat D communicates with the groove 48 through the groove 48, the small diameter part 57, the communication hole, and the small diameter part 55.
5 and boat A. Therefore, high pressure hydraulic oil is sent from boat C to boat B, and return hydraulic oil is returned from boat A to boat D. Note that when the spool 44 moves from the center position to the left and right, the boat C and the boat D
It is desirable to establish communication between boat C and boat B or boat A slightly before the communication between boat C and boat B or boat A is interrupted. Pressure springs 60 and 61 are provided between the spool 44 and both end walls of the valve housing 43, and when no pilot oil pressure is applied to the pilot oil chambers 49 and 50, the spool 44 is returned to the center position and the switching is performed. The valve 18 is switched to a neutral position.

Next, to explain the operation of this embodiment, the first
In the figure, the first and second solenoid valves 28 and 29 are now
Assume that both are in the neutral position and the valve operating switching valve 19 is in the left position.

When the hydraulic pump P is driven, high-pressure hydraulic oil discharged from the hydraulic pump P is guided to the boat C of the pump drive switching valve 18 through the high-pressure oil passage 15 and the branch high-pressure oil passage 1j6, and also through the branch high-pressure oil passage 17. It is guided to a switching valve 19 for valve operation. When the first solenoid valve 28 is in the neutral position, no pilot oil pressure is applied to the pilot oil chambers 49, 50 (Figure 2) of the pump drive switching valve 18, so the switching valve 18 is in the neutral position. maintained.
Therefore, the boat C communicates with the boat D via the throttle hole 59, and the high-pressure hydraulic oil discharged from the hydraulic pump P passes through the boat C1 throttle hole 59, the boat D, and the return oil path 20. The oil is refluxed to the oil tank T. However, since this circuit is throttled by the throttle hole 59, the back pressure
In other words, the pressure inside the tube 16 increases. As a result, the branch high pressure oil passage 17 is also supplied with sufficiently high pressure hydraulic oil. This hydraulic oil flows from the valve operating switching valve 19 to the oil passage 23.
It flows into the base chamber c of the valve chamber 10 through the valve 1.
2 to the pump cylinder 1'' side (lower position in the figure). When the valve 12 moves to the end on the tip chamber d side,
Valve 12 contacts the valve stem of check valve 14 to open check valve 14. Therefore, the hydraulic oil in the oil passage 23 is guided to the first solenoid valve 28 via the pilot oil passage 37, the check valve 14, and the pilot oil passage 35. During this time,
The hydraulic oil in the front chamber d of the valve chamber 10 is returned to the oil tank T via the oil passage 24, the valve operation switching valve 19, and the return oil passage 20. Here, the first and second solenoid valves 28, 29
When both are operated to switch to the right position, that is, the normal rotation position, the hydraulic oil guided through the pilot oil passage 35 flows into the first solenoid valve 28 and the pilot oil passage 31.
The oil flows into the pilot oil chamber 50 (FIG. 2) on the right side of the pump drive switching valve 18 through the pump drive switching valve 18, and pilot oil pressure is applied from the right side to switch it to the right position.

At this time, the hydraulic oil in the pilot oil chamber 49 on the left side passes through the pilot oil passage 30, the first solenoid valve 28, the pilot oil passage 3 male check valve 13, and the pilot oil passage 36, and then flows through the oil passage 2.
It is discharged to 4. When the pump drive switching valve 18 is switched to the right position, high-pressure hydraulic oil from the hydraulic pump P passes through the branch high-pressure oil passage 16, the switching valve 18, and the oil passage 22 to the tip chamber b of the second hydraulic cylinder 2''. '' and retracts the drive piston 4''.

At the same time, the hydraulic oil in the base chamber a'' of the second hydraulic cylinder 2'' flows into the base chamber a of the first hydraulic cylinder 2 through the connecting oil passage 25, and advances the driving piston 4 thereof.
The hydraulic oil in the tip chamber b of the first hydraulic cylinder 2 is supplied to the oil passage 21.
, the switching valve 18, and the return oil path 20, and are returned to the oil tank T. In this state, the pump cylinder 1'', which is in the suction process, sucks in a fluid such as concrete from a hopper (not shown), and the pump cylinder 1, which is in the discharge process, pumps the fluid into the discharge pipe 11 through the valve 12. Exhale.

When the driving piston 4 approaches the tip of the first hydraulic cylinder 2, it presses the valve rod 9 of the control valve 6 to open the valve 6, and the inflow and outflow boats 7 and 8 are communicated with each other.

As a result, the high pressure hydraulic oil is delivered to the tip chamber b'' of the second hydraulic cylinder 2'', the pilot oil passage 40, the control valve 6, the pilot oil passage 38, the second solenoid valve 29, and the pilot oil passage 3.
3, pilot oil pressure is applied to the right side of the valve operating switching valve 19 to switch the switching valve 19 to the right position. During this period, the hydraulic oil in the pilot oil chamber on the left side of the switching valve 19 flows through the pilot oil passage 32 and the second solenoid valve 29.
, pilot oil passage 39, control valve 6'', pilot oil passage 4
1, the tip chamber b1 of the first hydraulic cylinder 2 is discharged to the oil tank T via the oil passage 21, the pump drive switching valve 18, and the return oil passage 20. When the valve operating switching valve 19 is switched to the right position, the hydraulic oil in the branch high pressure oil passage 17 is transferred to the switching valve 19.
, flows into the tip chamber d of the valve chamber 10 via the oil passage 24,
Place the valve 12 on the pump cylinder 1 side (upper position in the figure)
Switch to .

When the valve 12 approaches the end on the side of the base chamber c, the check valve 13
opens. Then, the hydraulic oil in the oil passage 24 is guided to the pilot oil passage 36, the check valve 13, the pilot oil passage 34, the first solenoid valve 28, and the pilot oil passage 30, and then to the pump drive switching valve 18 from the left side. Apply pilot oil pressure and switch it to the left position. During this time, the valve chamber 10
The hydraulic oil in the base chamber C and the hydraulic oil in the pilot oil chamber 50 on the right side of the switching valve 18 are returned to the oil tank T via the oil passage 23, the valve operation switching valve 19, and the return oil passage 20. When the pump drive switching valve 18 is switched to the left position, high-pressure hydraulic oil flows into the tip chamber b of the first hydraulic cylinder 2 through the branch high-pressure oil passage 16, the switching valve 18, and the oil passage 21, and the pump drive While retracting the piston 4, the hydraulic oil in the base chamber a is made to flow into the base chamber a'' of the second hydraulic cylinder 2'' through the connecting oil passage 25, and the driving piston 4'' is advanced.In this state, the pump cylinder 1 sucks the fluid, and the pump cylinder 1″ pumps the fluid. Drive piston 4″
approaches the tip of the second hydraulic cylinder 2'', the control valve 6'' opens, and the hydraulic oil in the tip chamber b of the first hydraulic cylinder 2 flows through the pilot oil passage 41, the control valve 6'', and the pilot oil passage. 39, second solenoid valve 29, and pilot oil passage 32
, and the valve operating switching valve 19 is switched to the left position again.

When the switching valve 19 is switched to the left position, the high pressure hydraulic oil introduced through the branch high pressure oil passage 17 causes the valve 1 to
2 is switched to the pump cylinder 1'' side, and the check valve 14
is opened, and the pilot oil pressure is applied to the pilot oil passage 35, the first
It is applied to the pilot oil chamber 50 on the right side of the pump drive switching valve 18 via the solenoid valve 28 and the pilot oil path 31.

In this way, the switching valve 18 is again switched to the right position, causing the drive piston 4'' to retreat and the other drive piston 4 to move forward.Thereafter, the above operating process is repeated.

In such an operating process, each time the drive piston 47 or 4'' contacts the valve rod 9, 9'' of the control valve 6, 6'', the pump drive switching valve 18 changes from the right position to the left position, or from the left position. The port C and the boat D are communicated through the throttle hole 59 even in the neutral position as described above, and the water is discharged from the hydraulic pump P. Since the high-pressure hydraulic oil is returned to the oil tank T without being shut off, there is no sudden circuit closure, and therefore surge pressure can be kept low.

If it becomes necessary to temporarily stop the piston pump while it is being driven, the first solenoid valve 28 may be returned to the neutral position.

Then, the pilot oil chamber 49 of the pump drive switching valve 18
, 50 communicate with each other and their pressures become equal, so the switching valve 18 is switched to the neutral position by the pressing force of the pressing springs 60, 61. In this neutral position, both boats A and B are shut off, so each hydraulic cylinder 2, 2'' is locked.Therefore, each drive piston 4, 4
Since the pump pistons 3, 3'', which are integrally connected to the pump pistons 3 and 3'', are fixed, reverse rotation of the piston pump is reliably prevented. It will be clear that in order to restart the piston pump once it has been stopped, it is sufficient to simply switch the first solenoid valve 28 to the forward rotation position.

While the hydraulic pump P is in operation, the pressure in the branch high-pressure oil passage 16 is increased by the throttle hole 59, and the pressure in the branch high-pressure oil passage 17 is therefore sufficiently high. The pilot oil pressure in the pilot oil passage 34 or 36 is also large, and the pump drive switching valve 18 can be smoothly and quickly switched to the left and right drive positions. Note that such stopping and driving of the piston pump can also be performed by stopping and driving the hydraulic pump P.

That is, when the hydraulic pump P is stopped, hydraulic oil is no longer sent to the branch high-pressure oil passage 17, and as a result, the pilot oil pressure disappears, the pump drive switching valve 18 is switched to the neutral position, and the piston pump is switched to the neutral position. If the hydraulic pump P is driven again after it is stopped and fixed, pilot oil pressure is generated and the three-way valve 18 is switched to the drive position. Furthermore, when it becomes necessary to drive the piston pump in reverse to draw fluid from the discharge pipe 11, both the first and second solenoid valves 28 and 29 can be operated to switch them to the left position. Bye 3. Then, when the valve 12 is on the pump cylinder 1'' side, the pump piston 3 moves backward, and when the valve 12 is on the pump cylinder 1 side, the pump piston 3''
However, a detailed explanation of this invention, which is not directly related to the present invention, will be omitted. In the above embodiment, the switching control of the pump driving switching valve 18 is performed directly in relation to the switching operation of the valve 12, but the switching operation of the valve 12 itself is controlled by the hydraulic cylinder 2.
.

As described above, according to the present invention, when the pump drive switching valve is in the neutral position, the high-pressure oil pressure source such as a hydraulic pump is communicated with the oil tank through the throttle hole. This eliminates the need to interrupt the main circuit of high hydraulic pressure, resulting in low surge pressure and a durable piston pump hydraulic actuator with low noise.

In addition, since the back pressure is increased by the throttle hole, a sufficiently large pilot oil pressure can be obtained even when driving a stopped piston pump, and the pilot oil pressure is used to switch the pump drive switching valve to the drive position. This allows things to be done smoothly and reliably.

[Brief explanation of the drawing]

Fig. 1 is an overall schematic diagram showing an embodiment of a hydraulic actuation device for a piston pump according to the present invention, and Figs. 2A, b, and c show a pump drive switching valve used in the above device in three different positions. FIG. 1,1''...Pump cylinder, 2,2''...Hydraulic cylinder, 3,3''...Pump piston, 4,4''...
・Drive piston, 6,6″...control valve, 18...pump drive switching valve, 43...valve housing, 44...spool, 59...throttle hole, A, B, C, D ...Boat, P
... Hydraulic pump, T... Oil tank.

Claims (1)

[Claims] 1. A pump cylinder on which a pump piston slides; A pump driving hydraulic cylinder connected to this pump cylinder and on which a driving piston integrally connected with the pump piston slides; A high-pressure hydraulic source to the hydraulic cylinder. a pilot-operated pump drive switching valve that switches the flow direction of supplied hydraulic oil to reciprocate the drive piston; and a pilot-operated pump drive switching valve that switches the flow direction of the supplied hydraulic oil to drive the drive piston back and forth; and a control valve that alternately switches the switching valve; the switching valve includes a valve housing having ports respectively connected to the hydraulic cylinder, the high-pressure hydraulic power source, and the oil tank; and a spool that slides within the valve housing and shuts off all ports connected to the hydraulic cylinder when the switching valve is in the neutral position; The hydraulic actuation device for a piston pump is provided with a throttle hole that allows communication between a port connected to the high-pressure hydraulic power source and a port connected to the oil tank.