JPS59226288A - Hydraulic pressure operating device of piston pump for sending fluid body by pressure - Google Patents

Abstract

PURPOSE:To reduce vibration and noise by a method wherein a reversible variable capacity type hydraulic pump is employed in the piston pump for sending fluid body, such as concrete not hardened or the like, which is provided with a common valve at the ends of a pair of pump cyliners arranged in parallel. CONSTITUTION:When the swash plate type both directions variable capacity type hydraulic pump 10 is driven into the normal direction under a condition that both normal and reverse changeover valves 44, 49 are at the left positions thereof, pump pistons 5a, 5b are driven for suction and delivery respectively by the delivery pressure of the pump through respective driving pistons 6a, 6b. When the driving piston 6b has passed a pilot port 48, a hydraulic pressure from a main oil path 9 acts on the changeover switch 43 by the high hydraulic pressure of a rear chamber 8b through a check valve 46 to switch the changeover valve 43. Accordngly, the swash plate of the hydraulic pump 10 is oscillated by a hydraulic servo 14, whereby the amount of delivery from a normal operation side delivery port 11 becomes zero and the same amount from a reverse operation side delivery port 13 is increased from zero. According to this method, the driving pistons 6a, 6b are operated into reverse directions smoothly thereafter.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic actuating device for a piston pump for pumping a fluid, and in particular, a pair of driving hydraulic cylinders are connected concentrically to a pair of pump cylinders, and a hydraulic actuating device for a piston pump for pumping a fluid is provided. A pump piston and a driving piston are respectively fixed to the pump cylinder side end and the driving hydraulic cylinder side end of the pair of piston rods that oil-tightly and displaceably penetrate the gap between the cylinders. The end opposite to the drive hydraulic cylinder is connected to a fluid pressure piston pump connected to a common discharge pipe via a valve that can be switched between a communication state and a cutoff state according to the operation of the piston rod. Relating to hydraulic actuators.

Conventionally, in such hydraulic operating devices, a switching valve is provided in the middle of an oil passage connecting a driving hydraulic cylinder and a fixed displacement hydraulic pump, and the switching operation of this switching valve causes the pump piston to alternately reciprocate. It is common to do so. However, in such a conventional device, when the switching valve is switched, a large amount of pressure discharged from the hydraulic pump must be released by the relief valve, and a large surge pressure is generated at this time. Furthermore, when the pump piston is activated after it has been stationary, a large amount of hydraulic oil flows into the drive hydraulic cylinder to speed up the activation of the pump piston, so a large surge pressure is generated at this time as well. It also causes vibrations and noise.

The present invention was made in order to eliminate such conventional drawbacks, and by using a variable displacement pump that can be forward and reverse, it is possible to eliminate the need for a drive hydraulic cylinder and a switching valve between the pumps, and it is possible to A hydraulic actuation device for a piston pump for pumping fluids that prevents the generation of surge pressure and smoothes the operation of the pump piston during startup, thereby reducing vibration and noise. The purpose is to provide.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A pair of parallel pump cylinders 1α and 2nd pump cylinder 1α,
1h, a pair of first and second driving hydraulic cylinders'
1a, 2b are arranged concentrically, and a partition wall 3 (Z) between the first pump cylinder 1α and the aX drive hydraulic cylinder 2a, as well as the second pump cylinder 1h and the second .
The first and second piston rods 4a pass through the partition wall 3z between the driving hydraulic cylinders 26 in an oil-tight manner and are freely displaceable.
4 b are placed respectively. Both piston rods 4a...
First and second pump pistons 5a+5'' that slide in the respective pump cylinders 1a, 1b are fixed to one end of the piston rods 4b, and a surface drive hydraulic cylinder 2a, First and second drive pistons 6a, 5b sliding within the circumferential drive hydraulic cylinder 2a are fixed respectively.

Inside 2h, the driving pistons 6a and 6h form front chambers Iσ and γh on the side of each pump cylinder 1a and 1b, and rear chamber 8a on the side remote from each pump cylinder 1σ and 7.6.
, F3b.

The tip chamber 7a of the first driving hydraulic cylinder 2a is communicated with the normal rotation side discharge port 11 of the hydraulic pump 10 via the first main oil passage 9, and the tip chamber 7b of the second driving hydraulic cylinder 2b is connected to the second main oil passage 9. It communicates with a reverse rotation side discharge port 13 of the hydraulic pump 10 via an oil passage 12 . Further, the respective rear chambers 8''+8b of the peripheral drive hydraulic cylinders 2a, 'lb are communicated with each other.In this way, the first and second drive hydraulic cylinders 2a, 2h
% First and second main oil passages 9, 12 and hydraulic pump 10
constitutes a closed circuit.

The hydraulic pump 10 is a swash plate type bidirectional variable displacement type, and the swash plate can be swung by the operation of the hydraulic servo 14 to change the discharge amount and the discharge direction.

Branch oil passage 1 branched from the first and second main oil passages 9 and 12
5 and 16 are connected via a 3-bot 3-position switching valve 11)
It is connected to an oil passage 19 provided with a leaf valve 18, and this oil passage 1
9 is connected to an oil tank 20.

The 3-bottom 3-position switching valve 17 is a pilot hydraulic type,
When the oil pressures of both branch oil passages 15 and 16 are the same pressure, the illustrated neutral position is maintained, and when the oil pressure of one branch oil passage 15 becomes higher than that of the other branch oil passage 16, the other branch oil passage 16 is held.
When the oil pressure of the other branch oil passage 16 becomes higher than that of one branch oil passage 15, the switching position brings the one branch oil passage 15 into communication with the oil passage 19. The relief valve 18 opens when the oil pressure on the 3-point/3-position switching valve 17 side of the oil passage 19 reaches a predetermined value, and therefore opens in either branch oil passage 15 communicating with the oil passage 19.
, 16, that is, main oil passage 9 or second main oil passage 12
It works to keep the oil pressure constant. Also, the first and second
The main oil passages 9 and 12 are interconnected via IJ-F valves 21 and 22, and these relief valves 21.
22 operates prior to the relief valve 18. That is, for example, when the oil pressure in the first main oil passage 9 exceeds a set value, the +71)-f valve 21 opens and a part of the hydraulic oil flows into the second main oil passage 12, and further the second main oil When the oil pressure in line 12 exceeds the set value, l)-f valve 18 opens and hydraulic oil flows out into oil tank 20.

In addition, a check valve 23 is installed in the middle of the J and second main oil passages 9 and 120.
．． 24, and the connecting point of these check valves 23 and 24 is connected to the first auxiliary hydraulic pump 25,
It is connected between a pair of relief valves 27 and 28 provided in the middle of an oil passage 26 that connects the oil tank 20. These check valves 23, 24 and IJ leaf valves 27, 28 function to supply hydraulic oil to the first and second main oil passages 9, 12.

A common valve chamber 29 is provided at the tip of each of the pump cylinders 1a, lb across them, and a discharge pipe 30 is connected to the center of this valve chamber 29. The valve chamber 29 includes a valve hole 31 that allows communication between the first pump cylinder 1a and the discharge pipe 30, and a second pump cylinder 1b.
A valve 33 having a valve hole 32 that can communicate with the discharge pipe 30 is slid together, and this valve 33 is driven by a hydraulic cylinder 34 for opening/closing and driving. That is, opening/closing 1
When hydraulic pressure is supplied to the head-side hydraulic chamber 35 of the driving hydraulic cylinder 34, the valve 33 is displaced and driven to a position that communicates the first pump cylinder 1a and the discharge pipe 30, and hydraulic pressure is supplied to the rod-side hydraulic chamber 36. At this time, the valve 33 is displaced and driven to a position where the second pump cylinder 1b and the discharge pipe 30 are communicated with each other.

an oil passage 37 connected to the head side hydraulic chamber 35 and the rod side hydraulic chamber 36 of the opening/closing driving hydraulic cylinder 34;
3B is a second auxiliary hydraulic pump 40 via a switching valve 39.
Alternatively, it is connected to the oil tank 20. A relief valve 42 is connected in the middle of the oil passage 41 between the switching valve 39 and the second auxiliary hydraulic pump 40. The switching valve 39 is a pilot hydraulic type two-position switching valve, and as shown in the figure, communicates the rod side hydraulic chamber 36 and the second auxiliary hydraulic pump 40, and connects the head side hydraulic chamber 35 to the oil tank 20. The right position communicates with the head side hydraulic chamber 35o6 and the second auxiliary hydraulic pump 40, and also communicates with the rod side hydraulic chamber 3.
The left position where the piston rods 6 are communicated with the oil tank 20 is switched depending on the operating positions of both piston rods 4a and 4b.

On the other hand, the pilot hydraulic pressure from the first auxiliary hydraulic pump 25 is applied to the hydraulic servo 14 through the switching valve 43 and the forward/reverse switching valve 4.
4, it is freely switched between forward and reverse directions and is supplied. The switching valve 43 is a pilot hydraulic 4-port 2-position switching valve, and operates the hydraulic servo 14 using the working pressure from the first auxiliary hydraulic pump 25 to swing the swash plate of the hydraulic pump 10 . Thereby, when the hydraulic pump 10 is discharging pressure oil from the normal rotation side discharge port 11, for example, after reducing the pressure oil discharge amount from the normal rotation side discharge port 11 to zero,
When the amount of pressure oil discharged from the reverse rotation side discharge port 13 is increased from zero to the maximum amount, and pressure oil is being discharged from the reverse rotation side discharge port 13, the operation is opposite to that described above.

At both ends of the switching valve 43, the pilot oil pressure from the first main oil passage 9 and the second main oil passage 12 is connected to the pilot check valve 45.
．． 46 respectively.

One of the pilot check valves 45 is for setting the discharge direction of the hydraulic pump 10 to the normal rotation side, and
The pilot oil pressure detected at the pilot port 47, which is interposed between the switch valve 43 and the switch valve 43, and which is provided near the partition wall 3α in the first driving hydraulic cylinder 2a, causes the second main oil passage 12 to also flow to the switch valve 43. Allow pressure oil flow. Also, the other check valve 46 is connected to the hydraulic pump 10.
This is to reverse the discharge direction of the first main oil passage 9.
The first main oil passage 9 also switches between the switching valve 43 and the switching valve 43 by the pilot oil pressure (detected at the pilot port 48 installed near the partition wall 3h in the second driving hydraulic cylinder 2h). Allow pressure oil to flow to. That is, when the first drive piston 6a passes through the pilot port 47 and moves toward the partition wall 3a, the pilot check valve 45 stops the action of pressure oil from the second main oil passage 12 to the switching valve 43. The position of the switching valve 43 is changed in order to allow the hydraulic pump 10 to rotate in the forward direction.Also, when the second driving piston 6b passes through the pilot port 48 and moves to the partition wall 3/I side, the other side The pilot check valve 46 allows the action of pressure oil from the first main oil passage 9 to the switching valve 43, and switches the position of the switching valve 43 to move the hydraulic pump 10 in the reverse direction.

The pilot oil pressure, which is also guided to the first and second main oil passages 9 and 12 via both pilot check valves 45 and 46, also acts on both ends of the switching valve 390 via the forward/reverse switching valve 49.

That is, when the hydraulic pump 10 is set to the normal rotation side and the first pump piston 5a is driven in the suction direction and the second pump piston 5b is driven in the discharge direction, hydraulic oil is supplied to the opening/closing driving hydraulic cylinder 340 and the Rondo side hydraulic chamber 36. is supplied, the switching valve 39 is switched to a position where the valve 33 closes the discharge port of the first pump cylinder 10L and communicates the second pump cylinder 1h with the discharge pipe 30. Also hydraulic pump 10
When the first pump piston 5a is driven in the discharge direction and the second pump piston 5b is driven in the suction direction by setting the pump to the reverse direction, hydraulic oil is supplied to the head side hydraulic chamber 35 of the opening/closing drive hydraulic cylinder 34, and the valve 33 closes the discharge port of the second pump cylinder 1h and closes the discharge port of the first pump cylinder 1a.
The switching valve 39 is switched to a position that communicates the discharge pipe 30 with the discharge pipe 30.

The forward/reverse switching valves 44 and 49 are electromagnetic switching valves, and regardless of the operating positions of both piston rods 4α and 4b, that is, both switching valves 3
Regardless of the switching position of 9.43, it is used to switch the discharge direction of the hydraulic pump 10 and the position of the valve 33.

Next, the operation of this embodiment will be explained. When the dual-direction switching valves 44 and 49 are in the left position, the hydraulic pump 10 is in the normal rotation state, and pressure oil is supplied from the normal rotation side discharge port 11. , pressure oil is supplied to the front chamber 7a of the first driving hydraulic cylinder 2α, the first driving piston 6a moves to the left, and the first pump piston 5a is suction driven, while the rear part of the second driving hydraulic cylinder 2b The chamber 8b is the first driving hydraulic cylinder 2
Since it communicates with the rear chamber 8a, the second drive piston 6h moves to the right and the second pump piston 5h is driven to discharge. At this time, hydraulic oil is supplied to the opening/closing drive hydraulic cylinder 340 and the Rondo side hydraulic chamber 36, and the valve 33 is connected to the discharge pipe 30.
This position is such that the discharge pipe 30 is communicated with the inside of the second pump cylinder 115 by being closed off from the first pump cylinder 1σ. Therefore, the fluid in the second pump cylinder 1b, such as fresh concrete, is discharged from the discharge pipe 30 by the second pump piston 5h, while the first pump cylinder 1
A fluid such as fresh concrete is sucked into the chamber a.

Next, the second drive piston 6h is connected to the pilot port 48.
When passing through, the rear chamber 8 of the second driving hydraulic cylinder 1b
Due to the high oil pressure at h, the oil pressure from the first main oil passage 9 acts on the switching valve 43 via the pilot check valve 46, and the switching valve 43 is switched. The swash plate is oscillated by the hydraulic servo 14 in accordance with the switching operation of the switching valve 43, and the hydraulic pump 10 reduces the discharge amount from the forward rotation side discharge port 11 to zero and the discharge amount from the reverse rotation side discharge port 13. increases from zero. Therefore, during the switching operation of the hydraulic pump 10, the moving speeds of both drive pistons 6a, 5b are gradually reduced and then reversed. That is, the oil pressure increases in the tip chamber γ2 of the second drive hydraulic cylinder 1b, the second drive piston 6z moves to the right, the second pump piston 51) shifts to suction drive, and the first drive piston 6a moves to the left. Then, the first pump piston 5a is driven to discharge.

At this time, the hydraulic pressure guided from the first main oil passage 9 via the pilot check valve 46 also acts on the switching valve 39,
9 is switched, and hydraulic oil is supplied to the head side hydraulic chamber 35 of the opening/closing driving cylinder 34. As a result, the valve 33 is driven, and the valve 33 communicates the inside of the first pump cylinder 1a with the discharge pipe 30, and the valve 33 communicates the inside of the first pump cylinder 1a with the discharge pipe 30.
The space between the engine and the discharge pipe 30 is closed off. Therefore, the fluid in the first bore ')''/l) cylinder 1a is discharged into the discharge pipe 3o by the first pump piston 5a, and the fluid is sucked into the second pump cylinder 1h by the second pump piston 5h. be done.

When the first drive piston 6α passes the pilot boat 41, the pilot oil pressure of the second main oil passage 12 acts on the switching valve 43.49 via the pilot check valve 45, and the discharge direction of the hydraulic pump 1o is changed. At the same time, the valve 33 is switched to the forward rotation side, and the valve 33 is switched to the second pump cylinder 1/I.
Switch to a position where the inside is communicated with the discharge pipe 30.

In this way, the first. The drive piston 6a and the first pump piston 5a, and the second drive piston 6h and the second pump piston 5h are driven alternately, and the position of the valve 33 is alternately switched so that the first and second pump cylinders 1a , IA are alternately discharged into the discharge pipe 30.

In this embodiment, pilot check valves 45 and 46 are used to allow flow in the opposite direction depending on the pilot oil pressure detected at pylon 1-horts 47 and 48, and the switching valve 39 is
．． 43 was made to switch, but the switching valve 39.43
The first and g2 drive pistons 6a, 6b are connected to the partition wall 3a.
, 3b is detected, and any configuration of the control valve may be used. Also, the partition wall 3a.

First and second drive pistons 6a are located on the end wall opposite to 3z.
, 675 can be configured so that the switching operation of the switching valves 39 and 43 is performed when the switching valves 39 and 675 come close to each other.

Furthermore, pilot oil for operating the hydraulic servo 14 may be obtained from the second auxiliary pump 40.

As described above, according to the present invention, the first main oil The hydraulic servo is connected to the hydraulic servo via a switching valve that switches when each drive piston reaches a preset position near the end wall in each drive hydraulic cylinder. Since it is connected to an auxiliary hydraulic pump that constantly discharges pressure oil, there is no need to provide a switching valve between the driving hydraulic cylinder and the hydraulic pump, and the generation of surge pressure at the time of switching is prevented. In addition, the hydraulic pump is of a variable displacement type, and the amount of pressure oil discharged during forward and reverse switching changes gradually, so a large amount of pressure oil does not act on the driving hydraulic cylinder at once, and therefore the pump piston starts. This makes the operation smooth and prevents surge pressure from occurring. As a result, it is possible to reduce vibration and noise caused by the generation of surge pressure.

[Brief explanation of the drawing]

The drawing shows one embodiment of the present invention, and is an overall hydraulic circuit diagram. 1a, 1b... pump cylinder, 'la, 'lb...
- Driving hydraulic cylinder, 3a, 3b... bulkhead, 4a,
4b... Piston salary, 5a, 56... Pump piston, 6σ.

Claims (1)

[Claims] A pair of driving hydraulic cylinders are concentrically connected to a pair of pump cylinders, and a pair of piston rods penetrating the partition wall between the two cylinders in an oil-tight and freely displaceable manner have ends on the pump cylinder side. A bong piston and a driving piston are respectively fixed to the end of the driving hydraulic cylinder, and the end of each pump cylinder opposite to the driving hydraulic cylinder is in a communicating state or a disconnected state depending on the movement of the piston rod. In a hydraulic actuation device for a piston pump for fluid pressure, which is connected to a common discharge pipe through a valve that can switch between A displacement hydraulic pump is connected via a first main oil passage and a second main oil passage so as to form a closed circuit, and the hydraulic servo is arranged so that each of the driving pistons is connected to an end within each driving hydraulic cylinder. Hydraulic operation of a piston pump for pumping fluid, characterized in that it is connected to an auxiliary hydraulic pump that constantly discharges pressure oil through a switching valve that switches when it reaches a preset position near a wall. Device.