JPS6125916B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a concrete pump that reciprocates pump pistons in a pair of pump cylinders by operating a pair of pump-driving hydraulic cylinders, and sucks in and pumps a fluid such as concrete. The present invention relates to a hydraulic actuation device for a piston pump such as the above.

Generally, in such a piston pump hydraulic system, high-pressure hydraulic fluid generated from the hydraulic pump is transferred to one chamber of each of a pair of pump-driving hydraulic cylinders by switching the pump-driving switching valve. The oil is supplied alternately, the other chambers of each hydraulic cylinder are communicated with each other, and the drive pistons sliding in each hydraulic cylinder are reciprocated in opposite directions. Each pump piston is connected to this drive piston, and 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 concrete is being pumped, the hydraulic oil in the hydraulic cylinder may flow toward the oil tank due to the weight of the concrete being pumped. If the flow is reversed, 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 hydraulic equipment, piping, etc. may 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 constructed as a pilot operated type, and it was automatically switched in relation to the operation of the hydraulic cylinder, so the piston pump that was temporarily stopped could be restarted. In order to generate a predetermined pilot oil pressure, that is, the pilot oil pressure that switches the switching valve from the neutral position to the operating position, it was necessary to shut off all ports of the pump drive switching valve that are connected to the hydraulic pump. .

In view of these requirements, in conventional piston pumps of this type, a three-position switching valve in which all ports are shut off in the neutral position is used as the switching valve for driving the pump, as shown in Japanese Patent Application Laid-Open No. 53-103205. It had become common to use it.

However, when such a three-position switching valve is used as a pump drive switching valve, each time the switching valve is switched in order to alternately supply high-pressure hydraulic oil from the hydraulic pump to each pump drive hydraulic cylinder. At the neutral position, the flow of hydraulic oil is temporarily interrupted. When the circuit is suddenly closed in this way, the pressure inside the circuit increases instantaneously. In other words, the surge pressure increases. the result,
In addition to generating noise, problems such as damage or breakage of hydraulic pumps, other hydraulic equipment, and piping systems occurred.

The present invention has been proposed in view of the above, and it is possible to use a three-position switching valve that shuts off all ports at the neutral position, unlike the conventional three-position switching valve, when the piston pump is temporarily stopped. The hydraulic pressure of the piston pump is such that it can reliably prevent reversal in the piston pump, and also reliably generate the pilot hydraulic pressure of the switching valve for driving the pump when the piston pump is redriven. The purpose is to provide an actuating device.

In order to achieve such an object, the present invention has the following features:
first and second pump driving hydraulic cylinders that are respectively connected to a pair of pump cylinders, and in which the pump pistons that are slidably connected to the respective pump cylinders and the drive pistons that are respectively connected are slidably connected; a pump drive switching valve for alternately supplying high-pressure hydraulic oil from the hydraulic pump to one chamber of each of the two hydraulic cylinders; a connection that connects the other chambers of the first and second hydraulic cylinders to each other; In the hydraulically actuated device for a piston pump, the switching valve for driving the pump is configured such that each port is not blocked at any switching operation position, and the connecting oil passage includes a hydraulic pump for driving the hydraulic pump. The hydraulic pump is characterized in that a normally closed type pilot-operated on-off valve that is opened by pilot hydraulic pressure guided from the hydraulic pump is interposed therein, and that the hydraulic pump further includes a stop device that can arbitrarily stop the operation of the pump.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. A pair of pump cylinders 1 arranged in parallel with each other,
First and second pump driving hydraulic cylinders 2, 2' are connected to the base end of the pump 1'. 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 integrally connected by connecting rods 5, 5', respectively. The driving pistons 4, 4' partition the inside of each hydraulic cylinder 2, 2' into base chambers a, a' and tip chambers b, b', respectively.

A pair of control valves 6, 6' are provided at the tip of each hydraulic cylinder 2, 2' to be activated when the drive piston 4, 4' reaches the tip. Each control valve 6, 6' is a pilot operated check valve that opens and closes an inlet port 7, 7' and an outlet port 8, 8', respectively, and its valve rod 9, 9' is connected to a hydraulic cylinder 2, 2'. The control valves 6, 6' are opened when the drive pistons 4, 4' come into contact with the valve rods 9, 9', It's becoming more and more closed when you get far away.

A common valve chamber 10 is provided at the tip of each of the pump cylinders 1, 1' 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 a and a tip chamber d. This basal chamber c
By alternately supplying hydraulic oil to the front chamber d and the valve 12, the valve 12 is reciprocated, and the pump cylinder 1 and the discharge pipe 11, or the pump cylinder 1' and the discharge pipe 11 are alternately connected. has been done. Additionally, pilot-operated check valves 13 and 14 are provided at both ends of the valve chamber 10, respectively, and are opened when the valve 12 approaches.

High pressure oil passage 15 connected to the discharge side of the hydraulic pump P
is branched into branch high-pressure oil passages 16 and 17, one branch high-pressure oil passage 16 communicates with a pump drive switching valve 18 which is a pilot-operated two-position switching valve, and the other branch high-pressure oil passage 17 is It communicates with a valve operating switching valve 19, which is also a pilot-operated two-position switching valve. In addition, these switching valves 18, 19
The hydraulic oil discharged from the tank is returned to the oil tank T via a return oil passage 20. Another oil passage 21, 22 coming out from the other side of the pump drive switching valve 18
are the tip chambers b and 2 of the hydraulic cylinders 2 and 2', respectively.
b', and also the switching valve 1 for valve operation.
Other oil passages 23 and 24 coming out from the other side of the valve chamber 9 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 connected to each other by a connecting oil passage 25, and a pilot operated on-off valve 26 is interposed in this connecting oil passage 25. This on-off valve 26 is a normally closed type that is pressed by a spring and switched to the right position in the figure to shut off the connecting oil passage 25 when no pilot oil pressure is applied. When pilot oil pressure is applied through 27, it is switched to the left position against the spring, so that the connecting oil passage 25 and therefore the base chambers a and a' of the hydraulic cylinders 2 and 2' are communicated with each other. . While the hydraulic pump P is in operation, its discharge pressure is applied to the on-off valve 2 as the pilot hydraulic pressure based on the resistance in the circuit.
6, the base chambers a and a' of the hydraulic cylinders 2 and 2' are maintained in a constant communication state, and in this state, for example, hydraulic oil is introduced into the tip chamber b of the hydraulic cylinder 2 and the drive piston 4 is activated. When moving to the base side, the hydraulic oil in the base chamber a is transferred to the connecting oil passage 2.
5 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 front chamber b' of the hydraulic cylinder 2' 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 are respectively disposed to switch and operate these. Pilot oil lines 30, 31 connected to two ports
By applying pilot oil pressure to the left and right sides of the pump drive switching valve 18, pilot oil passages 32 and 3 connected to two ports on one side of the second solenoid valve 29 are applied.
3, pilot oil pressure is applied to the left and right sides of the valve operating switching valve 19.

On the other hand, the two ports on the other side of the first solenoid valve 28 are connected to check valves 13 and 1 provided at both ends of the valve chamber 10 via pilot oil passages 34 and 35.
4 inlet ports, respectively. Outflow ports of the check valves 13 and 14 are communicated with oil passages 24 and 23 through pilot oil passages 36 and 37, respectively. Also, the second solenoid valve 2
The two ports on the other side of 9 are pilot oil passage 3.
8, 39 to the inlet ports 7, 7' of the control valves 6, 6'. The outflow port 8 of the control valve 6 is connected to the tip chamber b' of the second hydraulic cylinder 2' through a pilot oil passage 40, and the outflow port 8' of the control valve 6' is connected to the first hydraulic cylinder through a pilot oil passage 41. The two front chambers b communicate with each other.

A relief valve 4 is provided between the high pressure oil passage 15 and the oil tank T.
2 is attached, and this relief valve 42 discharges the hydraulic oil in the oil passage 15 when the oil pressure in the high pressure oil passage 15 becomes higher than the set value to maintain the oil pressure below the set value. It's becoming like that.

The hydraulic pump P is equipped with a stop device (not shown) that can arbitrarily stop its operating state, and as described later, in the present invention, the operation of the piston pump is temporarily stopped by temporarily stopping the hydraulic pump P. It is becoming possible to do this.

The pump drive switching valve 18 is configured so that each port is not blocked at any switching operation position in order to suppress a rise in surge pressure in the hydraulic circuit at the time of switching operation. In particular, in this embodiment, The hydraulic oil supplied from the hydraulic pump P through the oil passages 15 and 16 is guided to the tip chamber b of the first hydraulic cylinder 2 through the oil passage 21, and the tip chamber b' of the second hydraulic cylinder 2' is guided through the oil passage 22. The hydraulic oil from the hydraulic pump is guided to the tip chamber b' of the second hydraulic cylinder 2' via the oil passage 22, and the hydraulic oil is passed through the return oil passage 20 and the oil tank T through the oil passage 22. It is composed of a two-position switching valve that can be switched to only two positions: a position that communicates the front chamber b of the oil tank with the oil tank T. Alternatively, a three-position switching valve 18' may be used, for example, as shown in FIG. 2, in which all ports communicate with each other in the neutral position. In this case, the hydraulic pump P in the neutral position
A throttle 45 is provided in the return oil passage 20 so that pilot oil pressure can be generated in the pilot oil passage 27 when the engine is re-driven.

The first and second solenoid valves 28 and 29 are three-position switching valves in which the right position in the figure is a normal rotation position and the left position is a reverse rotation position.

Next, the operation of this embodiment will be explained. Now, switch the pump drive switching valve 18 to the right position, move the drive piston 4 in the first hydraulic cylinder 2 to the most retracted position (leftmost position in the drawing), and move the drive piston 4 in the second hydraulic cylinder 2' ′ are held at the most advanced position (the rightmost position in the drawing), the first and second solenoid valves 28 and 29 are respectively switched to the right position, that is, the forward rotation position, and the hydraulic pump P
Suppose you drive.

At that time, assuming that the valve operating switching valve 19 is in the left position as shown in the figure, the high pressure hydraulic oil pumped by the hydraulic pump P is transferred to the high pressure oil passage 15, the branch high pressure oil passage 17, and the valve operating switching valve 19. , and the oil passage 23, it flows into the base chamber c of the valve chamber 10, and switches the valve 12 to the pump cylinder 1' side (lower position in the figure). When the valve 12 moves to the end of the front chamber d side, the valve 12 closes to the check valve 1.
4, the check valve 14 opens. Then, the hydraulic oil in the oil passage 23 is transferred to the pilot oil passage 3.
7, guided to the check valve 14, pilot oil passage 35, first solenoid valve 28, pilot oil passage 30,
Apply pilot oil pressure to the pump drive switching valve 18 from the left side and switch it to the left position. During this time, the hydraulic oil in the tip chamber d of the valve chamber 10 is
The hydraulic oil in the pilot oil chamber on the right side of the pump drive switching valve 18 is returned to the oil tank T via the oil passage 24, the valve operation switching valve 19, and the return oil passage 20. The oil is discharged to the oil passage 24 via the solenoid valve 28, the pilot oil passage 34, the check valve 13, and the pilot oil passage 36.

When the pump drive switching valve 18 is switched to the left 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'. ′. During this time, pilot oil pressure is generated in the pilot oil passage 27 due to resistance in the circuit, and the on-off valve 26
is switched to the left position against the pressing force of the spring. Therefore, the first and second hydraulic cylinders 2,
Since the base chambers a and a′ of 2′ are in communication with each other,
The hydraulic oil flowing into the tip chamber b' of the second hydraulic cylinder 2' causes the drive piston 4' to retreat. Thereby, 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, causing the drive piston 4 to move forward. During this time, the hydraulic oil in the front chamber b of the first hydraulic cylinder 2 passes through the oil passage 21, the switching valve 18, and the return oil passage 20 to the oil tank T.
is refluxed to.

In this state, the pump cylinder 1' in the suction process sucks in a fluid such as concrete through a hopper (not shown), and the pump cylinder 1 in the discharge process pumps the fluid into the discharge pipe 11 through the valve 12. Exhale.

When the drive piston 4 approaches the tip of the first hydraulic cylinder 2, that is, reaches the most forward position (at this time, the drive piston 4' is at the most retracted position), it presses the valve rod 9 of the control valve 6 and closes the valve. 6 is opened, and its inflow and outflow ports 7 and 8 are communicated. the result,
The hydraulic oil in the tip chamber b' of the second hydraulic cylinder 2' is
Pilot oil pressure is applied to the right side of the valve operating switching valve 19 through the pilot oil passage 40, control valve 6, pilot oil passage 38, second solenoid valve 29, and pilot oil passage 33, and the switching valve 19 is moved to the right position. Switch. 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, the second solenoid valve 29, the pilot oil passage 39, the control valve 6', the pilot oil passage 41, and the tip of the first hydraulic cylinder 2. The oil is discharged to the oil tank T through the chamber b, 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 flows into the tip chamber d of the valve chamber 10 via the switching valve 19 and the oil passage 24, and the valve 12 is pumped. Switch to the cylinder 1 side (upper position in the figure). 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 31, and then to the pump drive switching valve 18 from the right side. Apply pilot oil pressure and switch it to the right position. During this period, the hydraulic oil in the base chamber c of the valve chamber 10 and the hydraulic oil in the pilot oil chamber on the left 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. be done.

When the pump drive switching valve 18 is switched to the right 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 transferred to the connecting oil passage 25.
and flows into the base chamber a' of the second hydraulic cylinder 2' through the on-off valve 26 to advance the driving piston 4'. In this state, the pump cylinder 1 sucks the fluid, and the pump cylinder 1' pumps the fluid.

When the drive piston 4' approaches the tip of the second hydraulic cylinder 2', that is, reaches the most forward position (at this time, the drive piston 4 is at the most retracted position), the control valve 6' opens and the first hydraulic pressure is The hydraulic oil in the front chamber b of the cylinder 2 is guided to the pilot oil passage 41, the control valve 6', the pilot oil passage 39, the second solenoid valve 29, and the pilot oil passage 32, and the valve operation switching valve 19 is again operated. Switch to left position.

Thereafter, the above operation process is repeated.

While the hydraulic pump P is being driven, as mentioned above, pilot oil pressure is generated in the pilot oil passage 27, and the on-off valve 26 is opened to open the connecting oil passage 2.
5 is maintained in a communicating state, but for some reason the pilot oil pressure drops and the on/off valve 26 closes.
If the hydraulic cylinders 2 and 2' are closed, the base chambers a and a' of the first and second hydraulic cylinders 2 and 2' are cut off, so that these hydraulic cylinders 2 and 2' are locked. As a result, the pressure in the tip chamber b or b' on the side to which hydraulic oil is supplied from the hydraulic pump P increases, and the pressure in the high pressure oil passage 15 communicating therewith also increases. Therefore, a large pilot oil pressure is generated in the pilot oil passage 27, and the on-off valve 26 is opened. In this way, the pump action continues as long as the hydraulic pump P is driven.

Next, if it becomes necessary to temporarily stop the piston pump while it is being driven, the hydraulic pump P is stopped. Then, the pressure inside the high pressure oil passage 15 decreases,
The pressure within the pilot oil passage 27 also decreases. As a result, the on-off valve 26 is switched to the right position by the pressing force of the spring, thereby blocking the connecting oil passage. Therefore, the base chambers a, a' of the first and second hydraulic cylinders 2, 2' are individually closed, so that each hydraulic cylinder 2, 2' is locked. In this way, the pump pistons 3, 3' integrally connected to the respective drive pistons 4, 4' are fixed, and the reversal of the piston pump is prevented.

In order to drive the piston pump once stopped again, it is only necessary to drive the hydraulic pump P. As a result, pilot oil pressure is generated again in the pilot oil passage 27, the on-off valve 26 opens, and the first and second hydraulic cylinders 2, 2' start operating again.

When it is necessary to reverse the piston pump, both the first and second solenoid valves 28 and 29 are operated to switch to the left position. Then, when the valve 12 is on the pump cylinder 1' side, the pump piston 3 moves back, and the pump cylinder 1
When the pump piston 3' is on the side, the pump piston 3' moves back and fluid is sucked from the discharge pipe 11. Since the other operations are the same as those during normal rotation, detailed explanation will be omitted.
In addition, in the above embodiment, the pump drive switching valve 18
The switching control is directly performed in relation to the switching operation of the valve 12, but the switching operation of the valve 12 itself is controlled in relation to the operation of the hydraulic cylinders 2 and 2'. , after all, the switching control of the switching valve 18 is indirectly controlled by the hydraulic cylinders 2,
2'.

As described above, according to the present invention, a pair of pump cylinders are connected to each other, and the pump pistons that are slidably connected to each of the pump cylinders and the drive pistons that are connected to each other are slidably connected to the first and second pump drives. a hydraulic cylinder; a pump driving switching valve for alternately supplying high-pressure hydraulic oil from the hydraulic pump to one chamber of each of the first and second hydraulic cylinders; the first and second hydraulic cylinders; and a connecting oil passage that connects the other chambers of the piston pump with each other, the connecting oil passage having a normally closed type pilot operated valve that is opened by pilot hydraulic pressure guided from the hydraulic pump. Since the hydraulic pump is equipped with an on-off valve and has a stop device that can arbitrarily stop the operation of the pump, if the hydraulic pump is stopped while the piston pump is being driven, the operation of each hydraulic cylinder is stopped. When the oil supply is cut off, the on-off valve is automatically closed, and the driving of each hydraulic cylinder is stopped and the hydraulic lock is quietly and reliably performed. It is possible to reliably stop driving the piston pump and prevent reverse rotation without using a 3-position switching valve that shuts off all ports.On the other hand, if the hydraulic pump is driven from the stopped state of the piston pump, each hydraulic cylinder The on-off valve is automatically opened by using the hydraulic oil as the pilot oil pressure.
The piston pump can be restarted without any trouble by driving each hydraulic cylinder.

Furthermore, since the pump drive switching valve is configured so that each port is not blocked at any switching operation position, high-pressure hydraulic oil from the hydraulic pump can be alternately supplied to each hydraulic cylinder while the piston pump is driving. Even if the switching valve is switched, the flow of high-pressure hydraulic oil is hardly blocked at that time, and therefore, as in the conventional device, high surge pressure is generated in the hydraulic circuit every time the pump drive switching valve is switched. There is no need to worry about this, and a piston pump hydraulic actuator with quiet operation and high durability can be obtained.

[Brief explanation of the drawing]

The figures show an embodiment of the hydraulic actuation device for a piston pump according to the present invention, with FIG. 1 being a general schematic diagram thereof, and FIG. 2 being a partial circuit diagram of a modification thereof. 1, 1'... Pump cylinder, 2... First hydraulic cylinder, 2'... Second hydraulic cylinder, 3, 3'...
...Pump piston, 4,4'...Drive piston,
6, 6'...Control valve, 18...Pump drive switching valve, 25...Connection oil passage, 26...Opening/closing valve, 27...
...Pilot oil passage, a, a'...Base chamber, b, b'...
...Front chamber, P...Hydraulic pump.

Claims (1)

[Claims] 1. Each of the pump cylinders is connected to a pair of pump cylinders,
first and second pump driving hydraulic cylinders in which the pump pistons and the connected driving pistons are respectively slidably fitted in each of the pump cylinders; one chamber of each of the first and second hydraulic cylinders; a pump drive switching valve for alternately supplying high-pressure hydraulic oil from a hydraulic pump; and a connecting oil passage that connects the other chambers of the first and second hydraulic cylinders to each other; In the hydraulically operated device, the pump drive switching valve is configured so that each port is not blocked at any switching operation position, and the connecting oil passage has a normal valve that is opened by pilot hydraulic pressure guided from the hydraulic pump. A closed type pilot-operated on-off valve is interposed, and the hydraulic pump further includes a stop device that can arbitrarily stop the operation of the pump.
Hydraulic actuator of piston pump. 2. The pump drive switching valve is positioned at two positions: one in which high-pressure hydraulic oil from the hydraulic pump is supplied to one chamber of the first hydraulic cylinder, and the other in which the high-pressure hydraulic oil is supplied to one chamber of the second hydraulic cylinder. The hydraulic actuation device for a piston pump according to claim 1, which is a two-position switching valve that can be switched only between two positions. 3. Claim 1, wherein the pump drive switching valve is a pilot operation switching valve, and further comprises a control valve that alternately switches the pilot oil pressure in relation to the operation of the first and second hydraulic cylinders. Hydraulic actuation device for a piston pump according to item 1 or 2.