JPS6343603B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a hydraulic cylinder of a working machine that uses the kinetic energy of a cylinder piston to strike an object, such as a hydraulic breaker, a pile driver, or a punching press.

The work energy of the cylinder piston is given by the product of the piston operating stroke, the pressure receiving area of the piston, and the fluid pressure acting on the piston. By the way, the piston's operating stroke and pressure-receiving area are determined by the size of the cylinder, but fluid pressure is generated by the piston load, so when the piston is subjected to a load near its dead center, as in a hydraulic breaker, for example, the Only fluid pressure is generated at this point, and the amount of stroke in this state is small, so the input kinetic energy is very small. Therefore, the output kinetic energy generated therefrom is also small.

For example, the fluid pressure operated motor described in JP-A-48-36574 has a piston cylinder housing a piston for hitting a chisel in the motor body and a spool cylinder housing a spool behind the piston cylinder. An alternating pressure piston chamber is disposed on the chisel side with the land in between, and a constant pressure piston chamber is disposed on the opposite side, and fluid pressure is constantly guided to the constant pressure piston chamber and the constant pressure spool chamber of the spool cylinder. The piston is retracted when the alternating pressure piston chamber receives fluid pressure from the constant pressure spool chamber and advances when the alternating pressure piston chamber communicates with the fluid outlet via the spool. The forward and backward limits of the piston are provided by switching the flow path when the spool, which operates in conjunction with the operation of the piston, reaches a predetermined position. Therefore, the stroke amount of the piston cannot be adjusted with this motor. For this reason, as a result of the piston's stroke end being dimensionally defined, the position of the stopper and workpiece must be set relative to the piston's stroke end position, which requires time and manpower to set the position. Moreover, work efficiency decreases. Moreover, since there is nothing that stipulates the minimum operating pressure at which the piston starts reciprocating, load pressure is only generated when the piston hits the object to be struck. Therefore, as mentioned above, when the piston receives a load near the bottom dead center, such as in a hydraulic breaker, the output kinetic energy is small because the stroke amount under load is small, and therefore the striking capacity is small. is low.

On the other hand, a hydraulic breaker that applies a large load pressure to the piston from the beginning of the striking stroke (Japanese Patent Laid-Open No. 1985
-52677) is proposed. This one is the 4th
As shown in the figure, a spring 53 is interposed on one side of a piston 52 fitted into a cylinder body 51, and working fluid from a hydraulic source 55 is supplied to the other side by a switching valve 54 to compress the spring 53. By releasing the working fluid to the tank 56 at the piston retraction limit, the piston 52 is pushed by the spring 53 and strikes the chisel 57. However, in order to obtain a large impact force, a strong and large spring is required, which makes assembly and adjustment of the impact force difficult, and a chamber to accommodate the large spring is required, making the entire cylinder large. There are drawbacks.

Therefore, in the present invention, the stroke end (lower limit) position on the workpiece side can be changed steplessly by pure hydraulic means, so that the position of the stopper and workpiece can be set regardless of the lower limit position of the piston. In addition, it is an object of the present invention to provide a cylinder control device that can realize highly efficient work suitable for working conditions by making the upper limit position of the piston variable and increasing the load pressure of the piston from the beginning of the piston's impact stroke. purpose.

The structure of the present invention for achieving the above object will be explained using FIGS. 1 to 3 corresponding to embodiments.

In the first invention, in a cylinder control device in which a double-rod type double-acting cylinder is selectively connected to a hydraulic power source and a tank by a three-position pilot switching valve, at least a pump port and a tank port are closed in a neutral position. First pilot chamber 19 at one end of position pilot switching valve 8, 40
of the two pilot chambers 20 and 21 at the other end, the second pilot chamber 20 has a pressure receiving area equal to that of the first pilot chamber 19 and has a throttle 24. A valve that is connected to the return line 10 that connects to the tank 9 through an interposed passage 25, and that communicates the oil pressure source side line 4 with the upstream side of the throttle 24 at a predetermined position of the piston rod 13 of the double-rod type double-acting cylinder 1, 41. The third pilot chamber 21 has a pressure receiving area smaller than that of the first pilot chamber 19, and is connected to the outlet port of the sequence valve 31 disposed in the branch line leading to the oil pressure source side pipe line 4. A throttle 3 is provided in the return passage 33 connecting the tank 9 and the
4 is interposed.

In the second invention, in addition to the first invention, a plurality of valve mechanisms are provided in parallel in the operating direction of the piston rod 13 to communicate the hydraulic pressure source side pipe 4 and the upstream side of the throttle 24 of the passage 25 at a predetermined position of the piston rod 13. The valve mechanism near the piston 36 and the upstream side of the throttle 24 are connected via the on/off valve 27.

At present, communication between the hydraulic power source side pipe 4 and the passage 25 is cut off, and the 3-position closed center switching valve 8, 40
is at position A, the piston 36 moves to the right in the figure (return stroke), and when the piston rod 13 reaches a predetermined position, the valve mechanisms 14, 17, 18, 3
8 and 39 communicate the upstream side of the throttle 24 of the passage 25 and the hydraulic pressure source side pipe line 4, and the pump hydraulic pressure acts on the pilot chamber 20, so that the spool pressing forces of the pilot chambers 19 and 20, which have the same pressure receiving area, are equal. In this case, when the sequence valve 31 is closed, the pilot chamber 2
Since 1 is approximately the tank pressure, the 3-position closed center switching valve 8 is switched to the neutral block position B by the springs 22, 22 at both ends. Therefore, when the piston 36 stops moving to the right (right stroke end, upper limit), the pump hydraulic pressure increases. This pressure is the sequence valve 31
When the set pressure exceeds the set pressure of It will move to the left (hitting stroke). In this case, since the piston 36 receives a high pressure substantially equal to the set pressure of the sequence valve 31 from the beginning of the impact stroke, large kinetic energy is generated.

In the striking process, communication between the hydraulic pressure source side pipe line 4 and the passage 25 is cut off when the piston 36 moves to the left, so the hydraulic pressure in the second pilot chamber 20 decreases and the spool pressing force on the pilot chamber 19 side decreases. overcomes the spool pressing force on the second pilot chamber 20 side, the 3-position closed center switching valves 8, 40 switch from position C to position A, the piston 36 reverses and moves to the right, and the above-mentioned operation is repeated. do.

In addition, in the second invention in which a plurality of valve mechanisms are provided, when the piston 36 moves to the right, if the on-off valve 27 is turned on in advance, the on-off valve 27 is turned off again by opening the valve mechanism connected to the on-off valve 27. When the valve mechanism on the side not connected to the on-off valve 27 is opened, the hydraulic pressure source side pipe 4 and the upstream side of the throttle 24 of the passage 25 communicate with each other, and the piston 36 stops moving to the right as described above. Therefore, the right stroke end position of the piston 36 can be selected by operating the on/off valve 27. Furthermore, by changing the opening degrees of the throttles 24 and 34, the rate of pressure drop in the pilot chambers 20 and 21 during the impact stroke is changed, so the reversal position of the piston can be changed.

Embodiments of the present invention will be described below with reference to the drawings.
In Fig. 1, 1 is a differential cylinder, one liquid chamber 2 is connected to a hydraulic pressure source 5 through lines 3 and 4, and the other liquid chamber 6 is connected to a line 7, a 3-port 3-position closed center cylinder with a neutral block position. It is selectively connected to a pipe line 4 communicating with a hydraulic power source 5 and a return pipe line 10 communicating with a tank 9 via a switching valve 8, and an object to be hit 11
An annular groove 1 is formed at the tip of the other piston rod 13, which has a smaller diameter than the piston rod 12 located on the side.
form 4. This annular groove 14 is connected to the casing 15
Oil chambers 16, 17, 18 whose pitches are equal to the width of the annular groove 14 are formed in the piston rod 13 fitting holes.
This is to connect two adjacent oil chambers.

Said 3 port 3 position closed center switching valve 8
(hereinafter referred to as a 3-position switching valve) is equipped with a first pilot chamber 19 at one end of the spool, and a second pilot chamber 20 having the same pressure receiving area as the first pilot chamber 19 at the other end, and a pressure receiving area larger than the pressure receiving area of the first pilot chamber 19. A third pilot chamber 21 having a small pressure-receiving area is provided, and springs 22 are provided at both ends of the spool for holding the spool at the neutral block position B when the pressing forces at both ends of the spool are equal.
Therefore, the first pilot chamber 19 is connected to the passages 23 and 3.
0 communicates with the conduit 3, and the second pilot chamber 20
The return pipe 1 is connected to the return pipe 1 by a passage 25 with a throttle 24 interposed therein.
0, and the oil chamber 18 at the right end is connected to the oil chamber 18 at the right end by the passage 26 upstream of the throttle 24 in the passage 25, and is turned from the closed position to the open position against the spring 44 when pilot pressure, which is an external command signal, is received. The oil chamber 1 at the left end is
The oil chambers 16 and 18 are connected to the pipe line 3 through an oil chamber 17 and a passage 29, which communicate with each other via an annular groove 14, respectively. That is, the oil chambers 16 and 17 and the annular groove 14 constitute one valve mechanism, and the oil chamber 1
7, 18 and the annular groove 14 constitute another valve mechanism. On the other hand, the third pilot chamber 21 is connected via a passage 32 to an outlet port of a sequence valve 31 that communicates with the pipeline 3 via a branch pipeline 30, and is connected to a return passage 33 connecting this connection point and the tank 9 with a throttle 3.
Interpose 4.

In addition, in the figure, 35 is an accumulator arranged in the conduit 4.

Since this embodiment has the configuration described above, 3
In the illustrated state in which the position switching valve 8 is switched to position A by the pump hydraulic pressure acting on the first pilot chamber 19, the liquid chamber 6 of the cylinder 1 is connected to the pipe line 7,
Tank 9 via 3-position switching valve 8 and return line 10
The piston 36 moves to the right in the figure because the pump hydraulic pressure is always acting on the other liquid chamber 2. While the piston is moving to the right, communication between the passages 29 and 25 is cut off, and no pump hydraulic pressure acts on the second pilot chamber 20. Also, when the pump hydraulic pressure is lower than the set pressure of the sequence valve 31, the sequence valve 34 is closed. Therefore, the third pilot chamber 21 is at approximately tank pressure. Annular groove 14 of piston rod 13
When the oil chambers 16 and 17 are communicated, the hydraulic pressure in the pipe line 3 is guided to the inlet port of the on-off valve 27, but when the on-off valve 27 is in the off position a, the pump hydraulic pressure acts on the second pilot chamber 20. Therefore, the three-position switching valve 8 remains in position A, and the piston 36 continues to move to the right. The annular groove 14 then connects the oil chambers 17 and 18.
When the passages 29 and 25 are communicated with each other, the pump hydraulic pressure acts on the second pilot chamber 20. Therefore, the spool pressing force of the first pilot chamber 19 and the total spool pressing force of the pilot chambers 20, 21 become equal, and the three-position switching valve 8 is switched to the neutral position B by the springs 22, 22 at both ends. 4 and the return line 10, respectively, the piston 3
6 stops moving to the right, pump pressure fluid is stored in the accumulator 35, and the pump fluid pressure gradually increases. When the pump hydraulic pressure exceeds the set pressure of the sea case valve 31, the sequence valve 31 opens and a part of the pump pressure liquid returns to the tank 33 through the throttle 34, and the hydraulic pressure generated upstream of the throttle 34 is transferred to the third pilot. As a result of the action on chamber 21, three-position switching valve 8 switches from position B to position C. As a result, the piston 36 receives pump hydraulic pressure on both sides thereof, and moves to the left in the figure due to the differential pressure based on the difference in pressure receiving areas on both sides.
In this striking process, high-pressure fluid approximately equal to the set pressure of the sequence valve 31 is applied from the hydraulic source 5 and the accumulator 35 to the piston 36 from the beginning of the leftward movement, so the piston 36 obtains large kinetic energy and hits the object to be struck. Crash into 11. In this impact stroke, when the piston 36 moves to the left, the annular groove 14 is connected to the oil chamber 18.
Since the oil chambers 17 and 18 are separated from each other and communication with the oil chambers 17 and 18 is cut off, the hydraulic pressure in the second pilot chamber 20, which communicates with the tank 9 via the throttle 24, decreases. Further, when the sequence valve 31 closes, the hydraulic pressure in the third pilot chamber 21 also decreases. As a result, when the spool pressing force on the pilot chamber 19 side overcomes the spool pressing force on the pilot chambers 20 and 21 side, the 3-position switching valve 8 switches to position A, but this switching speed is lower than that of the throttles 24 and 34.
This can be changed by adjusting the opening degree. In this embodiment, the opening degrees of the throttles 24 and 34 are determined in advance so that the three-position switching valve 8 is switched from position C to position A after the piston rod 12 hits the object 11 to be hit. Therefore, after hitting the object 11, the piston 36 reverses and moves to the right in the figure (return stroke), and thereafter repeats the above-described operation.

Note that when the sequence valve 31 is open even when the piston is moving to the right, the pump hydraulic pressure is acting on the third pilot chamber 21 (the third pilot chamber 21
(The pressure receiving area of , the three-position switching valve 8 is switched from position A to position C all at once. That is, as soon as the piston 36 reaches the right stroke end (upper limit), it reverses and moves to the left. Furthermore, if the on-off valve 27 is switched to position b by the pilot pressure, which is an external command signal, the pump hydraulic pressure acts on the second pilot chamber 20 at the point where the oil chambers 16 and 17 communicate with each other through the annular groove 14, and the pump is switched to the third position. The switching valve 8 is switched from position A to position B or position C. Therefore, by operating the on/off valve 27, the upper limit of the piston can be selected in two ways, and the reciprocating stroke amount and number of reciprocations of the piston can be changed.

Furthermore, in this embodiment, an accumulator 35 is disposed in the conduit 4, but since the cylinder 1 is a double-rod type double-acting cylinder that requires a small amount of supplied oil, it can be used without any particular accumulator. A large amount of kinetic energy can be obtained.

What is shown in FIGS. 2 and 3 are modified embodiments of the one shown in FIG. 1, respectively. The one shown in FIG. 2 uses a detection rod 37 to detect the end of the rod 13 and open the valve instead of the two valve mechanisms consisting of the annular groove 14 and oil chambers 16, 17, and 18 of the piston rod 13 in FIG. Two 2-port 2-position switching valves 3
8 and 39 are arranged along the longitudinal direction of the piston rod 13, and the inlet port is connected to the pipe line 3 via the passage 29, and the outlet port of the two-port position switching valve 39 is the on-off valve explained in FIG. 27 is inserted into the passage 28, and the 2-port 2-position switching valve 3
8 outlet ports are connected to passage 2 by passage 26, respectively.
It is connected upstream of the aperture 24 of No. 5. The one shown in Fig. 3 replaces the 3-port position closed center switching valve 8 of Fig. 1 with the 4-port 3-position closed center switching valve 4.
0, and accordingly, the liquid chamber 2 of the double-rod type double-acting cylinder 41 is connected to the 4-port 3-position closed center switching valve 40 (hereinafter referred to as 3-position switching valve) through the pipe 42 and the liquid chamber 6 through the pipe 7. This is what I did.
These embodiments have similar effects to those shown in FIG. In the case shown in FIG. 3, the pressure receiving areas of the liquid chambers 2 and 6 of the cylinder 41 can be made equal. That is, in the 3-position switching valve 8 of FIG. 1, the liquid chamber 2 is always connected to the hydraulic pressure source 5 via the pipes 3 and 4, so the 3-position switching valve 8 is switched to position C and the piston 36 is moved as shown in the figure. In order to move the liquid to the left, it was necessary to make the pressure receiving area of the liquid pressure 6 larger than the pressure receiving area of the liquid chamber 2, but in the case of the 3-position switching valve 40 shown in FIG. is also connected to the hydraulic source 5 or the tank 9 via the 3-position switching valve 40, and when the piston 36 is operated in either the left or right direction, one hydraulic pressure chamber is always connected to the hydraulic source and the other hydraulic chamber is connected to the tank. Therefore, the pressure receiving areas of the liquid chambers 2 and 6 can be made equal. If the pressure-receiving areas of the liquid chambers 2 and 6 are made equal, a so-called AB connection in which only both actuator ports are connected can be achieved as a flow pattern at the neutral position of the three-position switching valve 40.

As explained above, according to the present invention, the other stroke end (lower limit) of the cylinder piston can be changed steplessly by the throttle communicating with the pilot chamber of the 3-position switching valve, so the lower limit of the piston is dimensionally There are no restrictions, and the position of the workpiece can be set regardless of the piston's stroke end position.
This has great advantages in terms of work and machine design.
In addition, at one stroke end (upper limit), the 3-position switching valve is switched and the piston is driven in reverse only when the pump fluid pressure exceeds the set pressure of the sequence valve, so the piston negative fluid pressure is increased from the beginning. As a result, the stroke speed and kinetic energy of the piston can be increased, and the striking ability at the time of hitting the workpiece can be greatly improved. Therefore, the cylinder control by the 3-position switching valve is achieved by a purely hydraulic configuration, which makes assembly and impact adjustment of the device relatively easy, and the pilot pressure of a part of the 3-position switching valve The secondary pressure of the sequence valve is used to reduce the number of valves, resulting in a compact configuration. In addition, one stroke end (upper limit) of the piston can be easily selected using an external command, so the number of reciprocating motions of the piston and the kinetic energy of the piston can be selected, allowing for high-efficiency work that is most suitable for the working conditions. can be realized.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram of one embodiment of the present invention;
The figure is a hydraulic circuit diagram of another embodiment using a valve mechanism different from the piston position detection valve mechanism in Figure 1.
A hydraulic circuit diagram of another embodiment in which the port is replaced with a three-position switching valve, and FIG. 4 is a sectional view including the hydraulic system of a conventional hydraulic breaker. 1...Differential cylinder, 5...Hydraulic power source, 8...3
Port 3 position closed center switching valve, 10...
Return pipe line, 11... hit object, 14... annular groove,
15... Casing, 16, 17, 18... Oil chamber, 19... First pilot chamber, 20... Second pilot chamber, 21... Third pilot chamber, 24,
34... Throttle, 27... On/off valve, 31... Sequence valve, 35... Accumulator, 36...
Piston, 37...Detection rod, 38, 39...2 port 2 position switching valve, 40...4 port 3 position closed center switching valve, 41...Double rod type double acting cylinder.

Claims (1)

[Scope of Claims] 1. A cylinder control device in which a double-rod type double-acting cylinder is selectively connected to a hydraulic power source and a tank using a 3-position pilot switching valve, in which at least a pump port and a tank port are closed in a neutral position. The first pilot chamber 19 at one end of the 3-position pilot switching valves 8, 40 is communicated with the oil pressure source side pipe line 4, and the second pilot chamber 20 has a pressure receiving area of 20, 21 at the other end. 1 pilot chamber 19 and is connected to the tank through a passage 25 with a throttle 24 interposed therebetween. The third pilot chamber 21 has a pressure-receiving area smaller than that of the first pilot chamber 19, and the outlet of the sequence valve 31 disposed in the branch path leading to the oil pressure source side pipe 4. A cylinder control device characterized in that a throttle 34 is interposed in a return passage 33 connected to a port and connecting this connection point and a tank 9. 2. In a cylinder control device in which a double-rod type double-acting cylinder is selectively connected to a hydraulic power source and a tank using a 3-position pilot switching valve, the 3-position pilot switching valve 8 closes at least the pump port and the tank port in the neutral position. . It is connected to the tank through a passage 25 with a throttle 24 interposed therebetween, and communicates the hydraulic pressure source side pipe 4 with the upstream side of the throttle 24 of the passage 25 at a predetermined position of the piston rod 13 of the double-rod type double-acting cylinders 1, 41. A plurality of valve mechanisms are arranged in parallel in the operating direction of the piston rod 13, and the valve mechanism near the piston 36 and the upstream side of the throttle 24 are connected via the on/off valve 27, and the third pilot chamber 2
1 has a pressure-receiving area smaller than that of the first pilot chamber 19, and is connected to the outlet port of the sequence valve 31 disposed in the branch path leading to the hydraulic power source side pipe 4, and is a return connecting this connection point to the tank 9. aisle 3
A cylinder control device characterized in that a throttle 34 is interposed in the cylinder 3. 3. The second pilot chamber 2 of the three-position pilot switching valve 8, 40 with at least the pump port and tank port closed in the neutral position during the entire range of the impact process.
The total spool pressing force on the 0 side is the first pilot chamber 1.
Claim 1 in which the opening degrees of the throttles 24 and 34 are selected so as to overcome the total spool pressing force on the 9 side.
Cylinder control device as described in section. 4. The cylinder control device according to claim 1, wherein an accumulator 35 is disposed in the hydraulic pressure source side pipe line 4. 5. A valve mechanism includes an annular groove 14 formed in the piston rod 13 and two oil chambers 1 formed in the insertion hole of the piston rod 13 and communicating through the annular groove 14.
7, 18, one oil chamber 17 is connected to the oil pressure source side pipe 4, and the other oil chamber 18 is connected to the passage 25 upstream of the throttle 24. The cylinder control device according to claim 1. 6. The cylinder control device according to claim 1, wherein the valve mechanism is a 2-port 2-position switching valve 38 that communicates the hydraulic pressure source side pipe 4 with the upstream side of the throttle 24 of the passage 25 through contact with the piston rod 13. . 7. The second pilot chamber 2 of the three-position pilot switching valve 8, 40 with at least the pump port and tank port closed in the neutral position during the entire range of the impact stroke.
The total spool pressing force on the 0 side is the first pilot chamber 1.
Claim 2 in which the opening degrees of the throttles 24 and 34 are selected so as to overcome the total spool pressing force on the 9 side.
Cylinder control device as described in section. 8. The cylinder control device according to claim 2, wherein an accumulator 35 is disposed in the hydraulic pressure source side pipe line 4.