JPS6233443B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a piston stroke adjustment device for a double-row, double-acting hydraulic cylinder.

A conventional hydraulically driven piston stroke adjustment device for a piston type concrete pump is explained with reference to Fig. 1.A is a hydraulic pump, b is a discharge pipe, c is a relief valve, d is a return pipe, e is an oil tank, and f is a gate. Cylinder switching valve, g ₁ , g ₂ are gate cylinder piping, h is main hydraulic cylinder switching valve, i ₁ ,
i ₂ is the main hydraulic cylinder piping, j and n are the main hydraulic cylinders, k and o are the hydraulic pistons, l and p are the piston rods, m is the communication pipe that connects the piston rod sides of the main hydraulic cylinders j and n, and A is the main hydraulic pressure A closed circuit consisting of piston rod side chambers of cylinders j and n and communication pipe 19, q and r are needle valves, _s1 is a hydraulic pipe that communicates needle valve q and discharge pipe b of the hydraulic pump, and _s2 is needle valve r A hydraulic piping that communicates between the hydraulic pump a and the return piping d, in which the pressure oil discharged from the hydraulic pump a passes through the discharge piping b, passes through the gate cylinder switching valve f and the gate cylinder piping _g1 , and then passes through the gate cylinder (not shown in Figure 1). ) to drive the gate cylinder. Further, the oil discharged from the gate cylinder is returned to the oil tank e through the gate cylinder piping _g2 , the gate cylinder switching valve f, and the return piping d. The gate cylinder switching valve f is a detection device (not shown in FIG. 1) that detects when the hydraulic pistons k or o of the main hydraulic cylinders j, n have reached the stroke end (the right end of the main hydraulic cylinder in FIG. 1).
Accordingly, the switching is performed when the hydraulic piston k or o reaches the stroke end. Further, pressure oil discharged from the hydraulic pump a is supplied to the piston side of the main hydraulic cylinder j or n through the discharge pipe b and the main hydraulic cylinder switching valve h, the main hydraulic cylinder pipe i ₁ or i ₂ . Now, suppose that pressure oil is supplied to the piston side oil chamber of the upper cylinder j in Fig. 1, the hydraulic piston k moves to the right, and as a result, the oil discharged from the piston rod oil chamber side of the main hydraulic cylinder j is It flows into the piston rod side of the lower cylinder n through the communication pipe m, and the hydraulic piston o moves to the left. As a result, the pressure oil discharged from the piston-side oil chamber of the main hydraulic cylinder n is returned to the oil tank e through the main hydraulic cylinder piping _i , the main hydraulic cylinder switching valve h, and the return piping d. On the other hand, the main hydraulic cylinder switching valve h is switched in conjunction with the operation of the gate cylinder by a detection device (omitted in FIG. 1) that detects the operation of the gate cylinder.
Also, needle valves q and r are called stroke adjustment valves, and are used during operation of the concrete pump.
When the needle valve q is opened, high pressure oil from the discharge pipe b flows into the closed circuit A through the hydraulic pipe _s1 needle valve q, the amount of oil in the closed circuit A increases, and the piston stroke becomes longer. Furthermore, when the needle valve r is opened, the oil in the closed circuit A flows out into the oil tank e, reducing the amount of oil and shortening the piston stroke.

In the piston stroke adjustment device for the hydraulically driven piston type concrete pump, ()
Since the piston stroke length is adjusted by opening and closing the needle valves q and r to increase or decrease the amount of oil sealed in the sealed circuit A, it is difficult to set the piston stroke length accurately. () When the operating conditions of the concrete pump change, the temperature of the oil sealed in sealed circuit A changes. In addition, the seals of the hydraulic pistons k and o of the hydraulic cylinders j and n and the seals of the needle valves q and r, etc.
It is extremely difficult to reduce internal leakage to zero, and the amount of oil in the sealed circuit A leaks little by little during concrete operation. When the above oil temperature changes or oil leakage occurs, the volume of oil in the sealed circuit A changes,
There was a problem in that unattended operation was difficult because the piston stroke length was unavoidable and the operator had to constantly monitor whether the piston stroke length was in a normal state.

The present invention addresses the above-mentioned problems, and is a double-row, double-row cylinder in which the piston rod-side oil chambers of a plurality of hydraulic cylinders are communicated through a communication passage, and a sealed circuit is formed by each piston rod-side oil chamber and the communication passage. In the dynamic hydraulic cylinder, a reed switch for detecting an optimum stroke length and a reed switch for detecting an excessive stroke length are provided at the stroke end position of the piston side oil chamber of one of the hydraulic cylinders, A magnet is provided for operating each of the switches, and when the piston of the hydraulic cylinder retreats, if the stroke length of the piston is shorter than the optimum stroke and the reed switch for detecting the optimum length does not operate, the switch is switched to the pressure oil supply position. If the stroke length of the piston is optimal and the reed switch for detecting the optimum stroke length is activated, the piston is switched to the neutral position, and if the stroke length of the piston is longer than the optimal stroke and the reed switch for detecting excessive stroke length is activated. It relates to an automatic piston stroke adjustment device for a double-row, double-acting hydraulic cylinder, characterized in that a solenoid valve that can be switched to an oil drain position is provided in a hydraulic pipe extending from the sealed circuit, and its purpose is to An object of the present invention is to provide an improved automatic piston stroke adjustment device for a double-row double-acting hydraulic cylinder that can always automatically adjust the piston stroke of the double-acting hydraulic cylinder to an optimum stroke length.

Next, an automatic piston stroke adjustment device for a double-row, double-acting hydraulic cylinder according to the present invention will be explained with reference to an embodiment shown in FIGS. 2 to 5. First, an explanation will be given with reference to the hydraulic circuit diagram in Fig. 2. In Fig. 2, 1 is a hydraulic pump, 2 is a discharge pipe, 3 is a relief valve, and 4 is a hydraulic circuit diagram.
1 is a return pipe, 5 is an oil tank, 6 is a gate cylinder switching valve, 7a and 7b are gate cylinder piping, 8 is a main hydraulic cylinder switching valve, 9 and 10 are main hydraulic cylinder pipes, 11 and 20 are main hydraulic cylinders, 12 ,3
3 is a hydraulic piston, 13 is a magnet embedded in the hydraulic piston 12, 14 and 32 are piston rods, 15 is a hole provided at one end of the piston rod 14, and 16 is a pipe protruding from the end surface of the hydraulic cylinder 11, on the hydraulic cylinder side. has a watertight structure. 17 is a reed switch (reed switch for detecting an optimum long stroke) provided inside the tip side of the pipe 16, 18 is a reed switch (reed switch for detecting excessive stroke length) provided inside the rear end side of the pipe 16, and 19 is a reed switch (reed switch for detecting excessive stroke length). Main hydraulic cylinder 11,
A communication pipe passing through the piston rod side of 20,
21 is a sealed circuit consisting of the piston rod side oil chambers of the main hydraulic cylinders 11 and 20 and the communication pipe 19;
22 is a hydraulic pipe communicating with the sealed circuit 21; 23;
24 is a needle valve, 25 is a solenoid valve, 26, 27 is a solenoid that switches the solenoid valve 25, 28, 29
30 is a hydraulic pipe that communicates the needle valve 23 and the flow rate regulating valve 28 with the discharge pipe 2 of the hydraulic pump; 31 is a hydraulic pipe that communicates the needle valve 24 and the flow rate regulating valve 29 with the return pipe 4; be.
Note that the hole 15 provided in the piston rod 14 is
When the hydraulic piston 12 moves backward (moves to the left in the figure), the protruding pipe 16 can be inserted into the position.
Made to the inner diameter and length. In addition, the reed switch 18 installed in the protruding pipe 16 is configured so that the pistons 12 and 33 of the main hydraulic cylinders 11 and 12 are reciprocating with the optimum stroke length, and the hydraulic piston 12 and 33 are reciprocating at the optimum stroke length.
The reed switch 17 is installed at a position where the contact closes due to the magnetic force of the magnet 13 when the hydraulic piston 12 is moved back the most. It is installed in Further, the pressure oil discharged from the hydraulic pump 1 passes through the discharge pipe 2, passes through the gate cylinder switching valve 6 and the gate cylinder piping 7, and is supplied to the gate cylinder (not shown in Fig. 2), thereby driving the gate cylinder. . The oil discharged from the gate cylinder is returned to the oil tank 5 through the gate cylinder piping 7, the gate cylinder switching valve 6, and the return piping 4. The gate cylinder switching valve 6 is operated by a detection device (not shown in FIG. 2) that detects when the hydraulic piston 12 or 33 of the main hydraulic cylinders 11, 20 has reached the stroke end (the right end of the main hydraulic cylinder in FIG. 2). , hydraulic piston 12 or 3
3 reaches the stroke end. Also, the pressure oil discharged from the hydraulic pump 1 is /
Main hydraulic cylinder 11 through discharge pipe 2, main hydraulic cylinder switching valve 8, main hydraulic cylinder pipe 9 or 10
Or it is supplied to the piston side oil chamber of 20. Assuming that pressure oil is now being supplied to the upper cylinder 11 in FIG. The oil flows into the piston rod side oil chamber of the lower cylinder 20, and the hydraulic piston 33 is driven to the left in the figure. As a result, the pressure oil discharged from the piston side of the main hydraulic cylinder 20 passes through the main hydraulic cylinder piping 10, the main hydraulic cylinder switching valve 8, and the return piping 4 to the oil tank 5.
be returned to. The main hydraulic cylinder switching valve 8 is switched in conjunction with the operation of the gate cylinder by a detection device (not shown in FIG. 2) that detects the operation of the gate cylinder. Also, needle valve 2
3 and 24 are called stroke adjustment valves, and when the needle valve 23 is opened during operation of the concrete pump, high pressure oil flows from the discharge pipe 2 through the hydraulic pipe 30, the needle valve 23, and the hydraulic pipe 22. The oil then flows into the sealed circuit 21, increasing the amount of oil in the sealed circuit 21 and lengthening the piston stroke.
Furthermore, when the needle valve 24 is opened, the oil in the closed circuit 21 flows out to the oil tank 5, the amount of oil decreases, and the piston stroke becomes shorter. Also, when the solenoid 26 of the solenoid valve 25 is energized, the discharge pipe 2 and the sealed circuit 21 are connected, and when the solenoid 27 is energized, the return pipe 4 and the sealed circuit 21 are connected, and the piston stroke becomes longer or shorter. . Further, the flow rate regulating valves 28 and 29 regulate the amount of oil flowing into (or flowing out of) the closed circuit 21 through the solenoid valve 25. In addition, in FIG. 3 showing the electric circuit of the automatic piston stroke adjustment device, 1
01 is the power supply, 102 is the power switch, 103 is the fuse, and 104 is the automatic stroke adjustment device.
ON/OFF switch, 105 is a relay contact that operates in conjunction with the forward rotation of the concrete pump, 106 is an electric wire that supplies electricity to each device of the automatic piston stroke adjustment device, 108 is an ON delay timer, 109 and 110 are OFF Delay timer, 1080 is ON delay timer 108 A
Contact, 1090 is B contact of OFF delay timer 109, 1100 is OFF delay timer 110
This is the A contact point. Further, 17 and 18 are contacts of the reed switch shown in FIG. 2, and 26 and 27 are solenoids of the electromagnetic valve 25, respectively. In addition, the power switch 10
2 is the power supply for the entire concrete pump equipment.
It is a switch that turns on and off. Further, the changeover switch 104 is turned OFF when the automatic piston stroke adjustment device is not used, and turned ON when it is used. Further, the relay contact 105 is a contact that is "closed" only when the concrete pump is operated in "normal rotation". When electricity is supplied to the wire 106, current immediately flows through the timer 108, and after a certain period of time, the contact 1080 closes, and thereafter, the contact 1080 continues to close until the electricity supplied to the wire 106 is cut off. . timer 10
Current flows through the reed switches 9 and 110 only when the reed switches 17 and 18 are closed. When current flows through the timer 109, the contact 1090 immediately opens, and when the current to the timer 109 is interrupted, the contact 1090 closes again after a certain period of time has elapsed. Further, when current flows through the timer 110, the contact 1100 immediately closes, and when the current to the timer 110 is cut off, the contact 1100 opens again after a certain period of time has elapsed. It also shows a timing chart of the operation of each of the above devices. In Figures 4 and 5, (C/P)
is a diagram showing the operating status of a concrete pump,
One rectangle indicates one stroke of the main hydraulic cylinder piston. (P in the diagram). (The straight line in the middle indicates the stopped state.) 104, 105, 1080, 18, 1
090, 17, and 1100 are diagrams showing the states of the changeover switch 104, relay contact 105, timer 108 contact 1080, reed switch 18 contact, timer 109 contact 1090, reed switch 17 contact, and timer 110 contact 1100, respectively. A low line indicates an open contact and a high line indicates a closed contact. 26 and 27 are the solenoid 26 of the electromagnetic valve 25
In the diagram showing the power supply status of 27, a low line indicates that no electricity is being supplied, and a high line indicates that electricity is being supplied.

Next, the operation of the piston stroke automatic adjustment device for the double-row, double-acting hydraulic piston will be explained. Assuming that the stroke length of the piston 12 is now shorter than the optimum stroke length, in order to activate the piston stroke automatic adjustment device, turn on the changeover switch 104 (A in Figure 4) and rotate the concrete pump in the normal direction. (B in Figure 4). In this way, current flows through the timer 108, and the contact 1080 closes after a certain period of time (C in FIG. 4). At this time, the piston 1 of the main hydraulic cylinder 11
Since the stroke length of reed switch 2 is shorter than the optimum stroke length, the magnet 13 of the hydraulic piston 12 does not allow reed switch 1
The position 8 is not reached and the contact of the reed switch 18 remains open. In this case, reed switch 1
Contact point 7 also remains open, of course. Therefore, both contacts 1090 and 1080 in the electrical circuit of solenoid 26 remain closed, and solenoid 26 remains closed.
6 is energized (FIG. 4 d), the solenoid valve 25 is switched to the left, and the closed circuit 2 of the main hydraulic cylinder is closed.
Oil is supplied to 1, and the piston stroke gradually becomes longer. When the piston stroke becomes longer and the hydraulic piston 12 moves back to the reed switch 18, the reed switch 18
The contact point will close only at that moment (E in Figure 4). When the contact of the reed switch 18 closes, current flows through the timer 109, and the contact 1090 immediately opens, cutting off the power to the solenoid 26, returning the solenoid valve 25 to neutral, and closing the closed circuit 21 of the main hydraulic cylinder. Oil supply is interrupted. The OFF delay time of the timer 109 is set aside for several strokes of the main hydraulic cylinder piston, so it
2 and 33), the timer contact 1090 does not close again, and the energization of the solenoid 26 continues to be interrupted. Sealed circuit 2
If the stroke becomes gradually shorter while the concrete pump is in operation after the oil supply to 1 is stopped, the hydraulic piston 12 will no longer retreat to the position of the reed switch 18, and the contact point of the reed switch 18 will be closed. It will not close (F in Figure 4). In this case, when the OFF delay time of the timer 109 has elapsed after the last activation of the reed switch 18, the contact 109 of the timer 109
0 is closed (G in FIG. 4), the solenoid 26 is energized (H in FIG. 4), and oil supply to the sealed circuit 21 is started again.

Next, assuming that the stroke length of the piston 12 is longer than the optimum stroke length, if the changeover switch 104 is turned on (A in Fig. 5) in the same way as described above, and the concrete pump is rotated in the forward direction (Fig. B) in the figure, the stroke length is too long, so when the hydraulic piston 12 retreats, both reed switches 18 and 17 are closed (C in Figure 5). When the contacts of the reed switch 18 are closed, the contacts 1090 are immediately opened as described above, and the current to the solenoid 26 is cut off. Immediately after forward rotation, contact 1080 of timer 108
The ON delay is working and it remains open for a certain period of time, and from immediately after starting normal rotation until the contact of reed switch 18 becomes closed (B to C in Figure 5). , preventing the solenoid 26 from being energized. When the contact of the reed switch 17 is closed in FIG. The oil inside is gradually drained and the piston stroke length begins to shorten. In order to smooth the operation of the solenoid valve 25, an OFF delay type is used for the timer 110, and the contact 1100 remains closed while the hydraulic piston 12 moves several strokes (D to D in Fig. 5).
E) It is becoming like this. Assuming that the stroke becomes gradually shorter during operation of the concrete pump after D in FIG. The solenoid 26 is closed, the solenoid 26 is energized again, and the sealed circuit 21 is supplied with oil.

In this way, in the automatic piston stroke adjustment device of the present invention, when the changeover switch 104 is turned ON and the piston is operated in the normal direction, the stroke length of the hydraulic piston remains unchanged even if there is a change in oil temperature or internal leakage. Since the stroke length is automatically adjusted to a value determined by the position, there is no need to pay attention to the stroke length of the piston during operation of the concrete pump, greatly reducing the burden on the operator. Furthermore, since the retracted position of the concrete piston can always be kept constant, providing the greasing port of the greasing device for the concrete piston at that position has the effect of efficiently lubricating the concrete piston.

Although the present invention has been described above with reference to embodiments, it goes without saying that the present invention is not limited to such embodiments, and that various design modifications can be made without departing from the spirit of the present invention. . For example, in the above embodiment, a set of two reed switches was shown, but by using only one reed switch, oil is supplied when the reed switch does not operate, and oil is drained when the reed switch is activated. Do one of the following. Alternatively, by using a combination of timers, it is also possible to provide a time period between refueling and oil draining in which neither of these operations is performed. Further, in the embodiment described above, the concrete pump is linked with normal rotation, but of course it may be linked with reverse rotation in addition to normal rotation. In addition, in the above embodiment, the stroke setting position was at one location, but if the hole 15 of the piston rod and the protruding pipe 16 were lengthened and reed switches were installed at several locations, and these could be selected by the switch, several types could be set. The piston stroke length can be freely selected with a single switch. Further, in the above embodiment, the detection device was provided only on one hydraulic cylinder, but the accuracy can be further improved by providing the detection device on both cylinders. Furthermore, in the above embodiment,
The hydraulic piping 30 branches from the hydraulic pump discharge piping 2, but in a concrete pump equipped with an accumulator, if it branches from the accumulator circuit, the supply pressure becomes almost constant and the amount of oil supplied can be stabilized. Also, if there is another suitable hydraulic power source, it may be branched from there. The piston position may be detected by any device capable of detecting the position of an object, such as a limit switch, photoelectric switch, or proximity switch, and is not particularly limited to a reed switch. Further, the needle valves 23 and 24 for manual stroke adjustment may not be provided, and the solenoid 26 or 27 of the solenoid valve 25 can be energized arbitrarily, or the solenoid valve 25 can be mechanically operated from the outside. In this case, the same effect as the provision of the needle valves 23 and 24 (manual adjustment of the piston stroke length) can be obtained.Also, the sealed circuit is not limited to the piston rod side, but may be provided on the piston side.

[Brief explanation of the drawing]

Figure 1 is a hydraulic circuit diagram showing a conventional piston stroke adjustment device for a double-row, double-acting hydraulic piston;
The figure is a hydraulic circuit diagram showing an embodiment of the piston stroke automatic adjustment device for a double-row, double-acting hydraulic piston according to the present invention, Figure 3 is its electric circuit diagram, and Figures 4 and 5 are timing charts of its operation. FIG. 11, 20... Hydraulic cylinder, 12, 13...
Piston, 13... Magnet for operating the switch, 17... Reed switch for detecting excessive stroke length, 18... Reed switch for detecting optimal stroke length, 19... Communication oil passage, 22... Hydraulic piping extending from the closed circuit. , 25... Solenoid valve, 30... Pressure oil supply side hydraulic piping, 31... Oil discharge side hydraulic piping.

Claims (1)

[Claims] 1. In a double-row, double-acting hydraulic cylinder in which the piston rod side oil chambers of a plurality of hydraulic cylinders are communicated by a communication oil passage, and a sealed circuit is formed by each piston rod side oil chamber and the communication oil passage, each of the hydraulic cylinders A reed switch for detecting an optimum stroke length and a reed switch for detecting an excessive stroke length are provided at the stroke end position of the oil chamber on the piston side of one of the hydraulic cylinders, and a magnet for operating each of the switches is provided on the piston of the same hydraulic cylinder. ,
When the piston of the hydraulic cylinder moves back, if the stroke length of the piston is shorter than the optimal stroke and the reed switch for detecting the optimal length does not operate, the piston is switched to the pressure oil supply position and the stroke length of the piston is optimal and the reed switch for detecting the optimal length does not operate. When the reed switch for detecting a long stroke is activated, the solenoid valve is switched to the neutral position, and when the stroke length of the piston is longer than the optimum stroke and the reed switch for detecting excessive stroke length is activated, the solenoid valve is switched to the oil draining position. An automatic piston stroke adjustment device for a double-row, double-acting hydraulic cylinder, characterized in that it is installed in a hydraulic pipe extending from a circuit.