JP2554476B2 - Speed-up circuit for hydraulic cylinders such as crushers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a crusher, a steel frame cutting machine or the like (hereinafter referred to as a crusher, which is attached to the tip of a hydraulic power shovel or the like and used for dismantling a reinforced concrete structure, a steel frame structure or the like. The present invention relates to a hydraulic circuit of a hydraulic cylinder for driving a crusher or the like).

[Conventional technology]

Hydraulic cylinders such as crushers used for dismantling reinforced concrete require a very large output, so the cylinder diameter becomes large and a large flow of oil must be supplied.
In practice, the amount of oil supplied by the installed hydraulic excavator is limited. Therefore, the speed at which the piston rod of the hydraulic cylinder moves back and forth has been a problem.

As a countermeasure against this, as shown in Japanese Patent Laid-Open No. 60-227001, by connecting a pressure booster to the cylinder and increasing the working pressure several times even with a small amount of oil, the cylinder diameter can be increased. A hydraulic circuit was used to make the piston rod move forward and backward faster.

[Problems to be solved by the invention]

However, in the case of the conventional example, in order to increase the work efficiency, it is necessary to further increase the speed of the piston rod until the pressure booster operates and shorten the time required for the piston rod to advance and retract. A possible way to do this is to increase the amount of oil supplied from the hydraulic pump, but as mentioned above, since the crusher is driven using the hydraulic power source of the hydraulic power shovel,
There are certain limits to changing this hydraulic pump,
It is necessary to devise a hydraulic circuit.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention has an oil side A which becomes a pressure oil side when a piston rod advances to a circuit composed of a conventional pressure booster, a first sequence valve and a first pilot check valve. A differential valve unit that functions to short-circuit the rear chamber and the front chamber of the hydraulic cylinder is provided between the oil passage B on the oil discharge side and the front chamber of the cylinder.

The differential valve unit has a pilot line which flows in from the pressure oil side, and the cracking pressure is set lower than that of the first sequence valve of the pressure booster. Further, a second pilot check valve is provided between the front chamber and the differential valve unit, which opens when the pilot pressure works when oil flows into the front chamber. This pilot line is connected to the oil passage B on the return side when the piston rod advances.

[Action]

Since the present invention has the above-mentioned configuration, when the operation valve is switched to the side where the piston rod advances (the state shown in Fig. 1) for crushing concrete, the pressure oil passes through the first pilot check valve to the rear of the hydraulic cylinder. Flows into the chamber.

On the other hand, the oil pushed out from the hydraulic cylinder front chamber merges with the oil on the pressure oil side through the second pilot check valve and the differential valve unit to form a so-called differential circuit. Therefore, the piston rod advances rapidly.

Next, when a load is applied to the piston rod, the pressure on the pressure oil side rises, and the pressure acts on the pilot chamber of the differential valve unit, the differential valve is switched and the differential circuit is eliminated. Then, since the front chamber of the cylinder communicates with the oil passage on the return side, the output of the cylinder increases.

When the load applied to the piston rod further increases, the pressure on the pressure oil side further increases, and the first sequence valve operates. Then, the pressure oil flows into the pressure booster through the first sequence valve, the pressure is continuously increased by several times, and the pressure oil is sent to the rear chamber of the cylinder. At this time, the first pilot check valve
It will not open because the pressure on the rear chamber side of the cylinder is high.

Next, when the crushing of the concrete is completed and the position of the operation valve is switched so that the piston rod returns (state of FIG. 4), the oil passage B which was the return side until now becomes the pressure oil side,
Since the first pilot check valve and the second pilot check valve are open and the rear chamber is connected to the oil tank,
Pressure oil flows into the front chamber of the cylinder and the piston rod retracts.

〔Example〕

 A first embodiment will be described with reference to FIGS.

Reference numeral 1 denotes a hydraulic cylinder in which a piston rod 2 is slidably incorporated, a rear chamber 3 and a front chamber 4 are formed, and oil supply / discharge ports 5 and 6 are provided, respectively. Reference numeral 20 is a hydraulic pump, 21 is a tank, and 19 is a three-position, four-direction operation valve for advancing and retracting a piston rod of a cylinder. A relief valve 57 is provided between this operation valve and the hydraulic pump.

Reference numeral 7 denotes a pressure booster, which is composed of a booster piston 23, a pressure booster box incorporating the booster piston 23, an automatic switching valve 33, a check valve 10, a right position detection valve 28, a left position detection valve 29, and the like.

The pressure booster 7 has an oil supply port 42, an oil discharge port 43, and a discharge port 44, and the discharge port 44 is connected to the oil supply / discharge port 5 of the cylinder rear chamber through an oil passage C45. Further, the oil supply port 42 is connected to the operation valve 19 via the first sequence valve 9 by an oil passage A40 which is on the pressure oil side when the piston rod 2 advances. On the other hand, drain port 4
3 is connected to the operation valve 19 by an oil passage B41 which is on the pressure oil side when the piston rod 2 retracts.

Inside the booster box, a booster piston 23 having a large diameter part in the center and a small diameter part on the left and right is slidably incorporated, and the right working chamber 53, the left working chamber 54 and the right high pressure chamber 55, the left A high pressure chamber 56 is formed.

In the oil passage that connects the left and right working chambers and the left and right high pressure chambers to the discharge port 44, a check valve 25 that is a free flow only when flowing to the right high pressure chamber is provided between the right working chamber 53 and the right high pressure chamber 55, Further, there is provided a check valve 24 which becomes free flow only when flowing from the right high pressure chamber 55 through the discharge port 44 to the rear chamber 3. The left working chamber 54 and the left high pressure chamber 56 are also provided with check valves 26 and 27 having the same function.

The left and right position detection valves 29, 28 are provided at the ends of the left working chamber 54 and the right working chamber 53, one end of which is biased by a spring and the other end of which protrudes into the left and right working chambers. It is a one-way, two-position valve that is pushed down by an inclined surface provided at the position to switch. Left position detection valve 29
Has a connection port 34 and a connection port 35, and the right position detection valve 28 is a connection port
36 and a connection port 37.

The connection ports 35 and 36 are connected by an oil passage, which is in the 2 position 4
It is connected to the pilot line H of the directional valve automatic switching valve 33. Further, the check valve 10 is provided between the automatic switching valve 33 and the oil drain port 43, the connection port 34 is connected to the oil passage connecting the automatic switching valve 33 and the first sequence valve 9, and the connection port 37 is It is connected to an oil passage between the automatic switching valve 33 and the check valve 10. Further, the left and right working chambers of the booster box are connected to the automatic switching valve 33, respectively.

The automatic switching valve 33 is in a normal state with a spring (first
(State in the figure), the pressure oil sent to the oil supply port 42 through the pump, the operation valve 19 and the first sequence valve 9 flows into the right working chamber 53 through the automatic switching valve 33, and the left working chamber 53 54 is connected to the return-side oil passage B41 through the automatic switching valve 33, the check valve 10, and the oil discharge port 43. Pilot working (second
In the state (in the figure), the connection between each working chamber and the oil passage is opposite.
An oil passage branched from the oil passage A40 is provided, and this oil passage is connected to an oil passage C45 connected to the rear chamber 3 via a first pilot check valve 8 having a pilot line connected to the oil passage B.

Reference numeral 11 is a differential valve unit having oil supply and drain ports 50, 51, 52. The oil supply / exhaust port 50 is connected to the oil path A40 via the oil path D60, and the oil supply / exhaust port 51 is connected to the oil path B via the oil path E61. The oil supply / drain port 52
Connects the pilot line F to the oil supply / discharge port 6 of the front chamber of the cylinder 1 through the second pilot check valve 14 connected to the oil passage E61.

The differential valve unit 11 includes a differential valve box 17
And a spool valve 15 slidably installed inside
And a pilot valve 16 having a large diameter portion and a small diameter portion. The spool valve 15 has one end negatively biased by a spring 18 and the other end abutting against a small diameter portion of the pilot valve 16, and an outer peripheral groove 58 is provided in the central portion thereof to connect the oil supply / exhaust port 50 and the oil supply / exhaust port 52. Contact or block. That is, in the state of FIG. 1, when the oil supply / exhaust port 50 and the oil supply / exhaust port 51 communicate with each other through the outer peripheral groove 58 and the spool valve 15 and the pilot valve 16 move to the state of FIG. The oil drain ports 50 and 51 are shut off, and instead, the small diameter portion of the pilot valve 16 connects the oil feed port 51 and the oil feed port 52.

The large diameter side of the pilot valve 16 is the pilot side, and the large diameter side diameter d ₂ is larger than the diameter d ₁ of the spool valve 15. The pilot line G of this valve is the second sequence valve installed in parallel.
Connect to oil passage D60 via 12 and check valve 13. The set pressure of the first sequence valve 9 is set higher than the set pressure of the second sequence valve 12.

The pressure when the spool valve moves due to the effect of the second sequence valve will be described below as the cracking pressure of the differential valve unit.

The second pilot check valve 14 is provided so that the piston rod of the cylinder 1 does not move by its own weight when the operation valve 19 is in the neutral position, and performs the same operation as the counter balance valve.

 Next, the operation will be described.

In order to move the piston rod 2 of the cylinder 1 forward, the operation valve 19 is brought into the state shown in FIG. When the piston rod 2 is not loaded and the oil pressure is low, the pressure oil flows in the oil passage A40.
Through the first pilot check valve 8 and the oil supply / drain port 5, and flows into the rear chamber 3 of the cylinder. On the other hand, the oil in the front chamber 4 is supplied / exhausted with oil 6 → second pilot check valve 14 → supply / exhaust with oil 52 →
Since the oil passage D60 merges with the oil passage A40 through the outer peripheral groove 58 → the oil supply / discharge port 50, the front chamber 4 and the rear chamber 3 are connected to each other, forming a so-called differential circuit, and the combined oil is It is sent to the rear room 3.

Next, when a load is applied to the piston rod 2 and the hydraulic pressure rises to reach the set pressure of the second sequence valve 12, pressure oil acts on the pilot line G of the pilot valve 16 and the pilot valve 16 resists the spring 18. As the spool valve 15 is pushed up, the oil supply / exhaust ports 50 and 52 are shut off and the oil supply / exhaust ports 51 and 52 communicate with each other, and the front chamber 4 of the cylinder passes through the oil passage B41 to the tank 21.
Connect to. This state is shown in FIG. Therefore, in this case, the forward speed of the piston rod 2 becomes slower but the output increases.

When the load of the piston rod further increases and the hydraulic pressure reaches the set pressure of the first sequence valve 9, the pressure oil passes through the first sequence valve 9 and flows into the automatic switching valve 33. When the automatic switching valve 33 is in the state shown in FIG.
It also flows into the right high-pressure chamber 55 via 25. At this time, left working chamber 54
Is connected to the oil passage B41 connected to the tank via the automatic switching valve 33 and the check valve 10, so the booster piston 23
Moves to the left to increase the pressure of the oil in the left high pressure chamber 56, and sends the high pressure oil to the rear chamber 3 via the check valve 27.

When the booster piston 23 comes to the stroke end on the left side, its large diameter portion pushes down the left position detection valve 29, so that the connection ports 34 and 35 are connected and the pressure oil flows into the pilot line H of the automatic switching valve 33 to automatically switch the valve. 33 is switched to the state shown in FIG. In this state, the right working chamber 53 has an automatic switching valve.
The oil from the oil passage B41 to the tank 21 via 33 and the check valve 10, while the pressure oil from the pump 20 flows through the oil passage A40, the automatic switching valve 33, the left working chamber 54 and the check valve 26 into the left high pressure chamber 56. , The booster piston 23 is moved to the right, and the oil in the right high-pressure chamber 55 is made high in pressure and sent from the oil passage C45 to the rear chamber 3 via the check valve 24. Booster piston 2
When 3 comes to the right stroke end, the right position detection valve 28
Is pressed down to connect the connection ports 36 and 37, so the automatic switching valve 33
Since the pilot line H is connected to the oil passage B41 on the oil discharge side via the check valve 10, the automatic switching valve 33 is restored by the force of the spring, and the state shown in FIG. 3 is obtained.

The above operation is automatically repeated to continuously feed the oil, which has been increased in pressure in each of the high pressure chambers 55 and 56, into the rear chamber 3 of the cylinder. In this state, the forward speed of the piston rod 2 is further reduced, but the output is increased to several times, and the object is crushed with a strong force.

Next, in order for the crusher to finish the crushing work of concrete or asphalt and to return the piston rod 2, the operation valve 19 is switched to the state shown in FIG. Pressure oil is oil passage
Although it flows to B41, since the check valve 10 blocks the inflow to the pressure booster 7, it flows to the oil supply / exhaust port 51 of the differential valve box 17 through the oil passage E61. At this time, the pilot line G of the pilot valve 16 is connected to the oil passage A40 through the oil passage D60 and is connected to the tank 21, so the pilot valve 16 is pushed downward.

On the other hand, since pressure oil also works on the lower end surface of the spool valve 15, it is pushed upward against the spring 18, and the pilot valve 16 and the spool valve 15 are in the states shown in FIG. Mouth 52 contacts. Then, the pressure oil in the oil passage B41 acts on the pilot lines of the first pilot check valve 8 and the second pilot check valve 14, so that the two valves are opened and the pressure oil flows into the front chamber 4 and the rear chamber. The oil of 3 returns to the tank through the oil passage A40 via the pilot check valve 8,
The piston rod 2 retracts.

FIG. 5 is a second embodiment of the differential valve unit portion,
The pilot line is connected to an oil passage connected to the oil supply / discharge port 50, and the cracking pressure is determined by the cross-sectional area of the strength of the spring 18, the diameter d ₁ of the spool valve 15 and the diameter d ₂ of the pilot valve 16.

FIG. 6 shows a differential valve unit in a general blocking diagram.

FIG. 7 is a diagram in which a crusher 101 adopting this circuit is mounted on a hydraulic power shovel 102.

FIG. 8 is a conventional hydraulic circuit diagram used in a crusher.

〔effect〕

Since the present invention has the circuit configuration as described above, when the piston rod is not loaded, a differential circuit that connects the front chamber and the rear chamber of the cylinder is configured to increase the forward speed of the piston rod. When the hydraulic pressure reaches the cracking pressure of the differential valve unit when the load is applied to the front chamber, the front chamber is connected to the tank side, so the speed is somewhat slowed but the output increases. When the load further increases and the first sequence valve opens, the pressure booster works to increase the output several times and destroy the object with a large force.

By switching the output and speed in three stages depending on the load condition applied to the piston rod as described above, the time required for the forward stroke can be shortened, and the time required for crushing work etc. can be shortened without using a large hydraulic cylinder. it can.

In addition, a large amount of force can be produced even with a small amount of oil, so the size can be reduced.

[Brief description of drawings]

1 to 4 are explanatory views of the first embodiment, FIG. 5 is a sectional view of the differential valve unit portion of the second embodiment, FIG. 6 is a block diagram of the differential valve unit, and FIG. The figure of the crusher mounted in the hydraulic power shovel, FIG. 8 is a circuit diagram of a prior art example. 1 ... Cylinder, 2 ... Piston rod 3 ... Rear chamber, 4 ... Front chamber 5 ... Supply / drain port, 6 ... Supply / drain port 7 ... Pressure booster 8 ... First pilot check valve 9 …… First sequence valve, 10 …… Check valve 11 …… Differential valve unit 12 …… Second sequence valve 14 …… Second pilot check valve 19 …… Operation valve, 40 …… Oil passage A 41 …… Oil passage B, 50, 51, 52 ... Oil supply and drain port

Claims (2)

(57) [Claims] 1. A pressure increasing device 7 having an oil supply port 42, an oil discharge port 43, and a discharge port 44 is mounted between an operation valve 19 and a hydraulic cylinder 1 such as a crusher, and connects the operation valve 19 and the oil supply port 42. A first sequence valve 9 is provided in the middle of the oil passage, and the oil passage branched from the oil passage A40 between the operation valve and the first sequence valve is connected to the discharge port 44 and the cylinder rear chamber 3 via the first pilot check valve 8. Oil path C4 to connect
5 and the operation valve 19 and the pressure booster drain 43
Is provided with an oil passage B41 for connecting the cylinder front chamber 4 and the oil passage B41.
In the circuit of a hydraulic cylinder such as a crusher in which the second pilot check valve 14 is provided in the middle of the oil passage connecting the two, in the middle of the oil passage connecting the second pilot check valve 14 and the oil passage B41,
A differential valve unit 11 having oil supply / exhaust ports 50, 51, 52 is provided, and the oil supply / exhaust port 50 is connected to the oil passage A40 by an oil passage D60 and an oil passage E61.
Connect the oil supply / drain port 51 to the oil passage B41, and
Is connected to the oil supply / exhaust port 6 in the front chamber of the cylinder 1 via the second pilot check valve 14, and the differential valve unit 11 has a structure having an internal pilot. The cracking pressure of the differential valve unit 11 is that of the first sequence valve 9. When the pressure is set lower than the set pressure, the oil supply / exhaust port 52 and the oil supply / exhaust port 50 communicate with each other until the cracking pressure is reached, and when the cracking pressure is exceeded, the differential valve unit switches and the oil supply / exhaust ports 52 and 50 A speed increasing circuit for a hydraulic cylinder of a crusher or the like, which is characterized in that the oil supply / exhaust port 50 is communicated with the oil supply / exhaust port 51. 2. The differential valve unit 11 includes oil supply and drain ports 50, 5
A spool valve 15 having 1, 52 and an outer peripheral groove 58 inside.
And a valve box for accommodating a pilot valve whose small diameter portion is in contact with the spool valve, and a large diameter end surface of the pilot valve 16 when the pressure in the internal pilot line G connected to the oil passage D60 exceeds the cracking pressure. The hydraulic cylinder speed increasing circuit according to claim 1, comprising a second sequence valve 12 for guiding oil, and switching communication between the oil supply / discharge oil ports 50, 51, 52 by movement of a spool valve and a pilot valve.