JPS6220789Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to a manual directional control valve with a safety device. A three-position control valve is used when hydraulic or pneumatic pressure is supplied to move equipment in the forward or reverse direction. If a dangerous situation occurs during operation, the danger can be avoided by sensing this and shutting off the hydraulic pressure. However, if when the supply of hydraulic pressure is resumed, the direction of movement is still in a direction that increases the danger, nothing will happen. When hydraulic pressure is resumed, the control valve must be in the position to reduce the risk or stop. Since it is a three-position switching valve, the lever can be switched to three positions: stop, forward direction, and reverse direction. Of these, the stop position has no effect on increasing or decreasing the danger. It is not possible to determine in advance which direction increases the risk and which direction reduces the risk. However, if you approach a dangerous situation while moving in the forward direction, you should be able to drive in the opposite direction to get out of the dangerous situation. In this way, when driving in forward or reverse direction,
If the hydraulic pressure is cut off due to a dangerous situation, it is preferable that the lever be switched to move in the opposite direction or be in the stopped position when restarting the supply of hydraulic pressure. This invention achieves these objectives,
Manual directional control with a safety device that requires the lever to be in a safe direction or stop position in order to resume hydraulic delivery, and prevents the lever from being switched in a direction that increases the danger. Regarding valves. Embodiments will be described below with reference to drawings showing examples. FIG. 1 is a schematic diagram of the hydraulic system. The hydraulic pressure sent out from the hydraulic pump 1 passes through the hydraulic pressure supply valve B and reaches the three-way control valve A according to the present invention. The control valve A can be switched to three positions: a left position A _l , a stop position A _p , and a right position A _r , and can rotate the hydraulic motor 3 in forward and reverse directions or stop it. The rotational force of the hydraulic motor 3 is transmitted to the load 5 via a transmission mechanism such as a gear 4. The load 5 is any mechanism that can be used, for example, to rotate the boom of a truck crane to the right or left. FIG. 2 is a circuit diagram showing the overall configuration of the safety device including the directional control valve A of the present invention. The control valve A can be switched to the left position A _l , the stop position A _p , and the right position A _r by manually moving the lever. Switches S ₁ , S ₂ , and S ₃ are switches that detect the position of control valve A, and the switches are closed when the ball fits into a recess 10 provided in the spool. The valve position detection switches S ₁ , S ₂ , and S ₃ are each
It closes when the right position A _r , the stop position A _p , and the left position A _l . The spool has a protrusion 11 and a lock pin 2.
1. A lock pin 22 prevents movement of the spool. Lock pin 21, 22
protrudes when the solenoids C ₁ and C ₂ are energized, and retreats when the solenoids are not energized and switches off.
S ₄ and S ₅ are in the pressed state. Self-holding relays R _a and R _b are set coils sc
The contact is closed or opened by the reset coil rc. When the set coil sc is energized, the contacts open, and this state is maintained even if the set coil no longer has current. When the reset coil rc is energized, the contacts open. X means the current to release the stopped state of the hydraulic supply valve B. If X is grounded when the appropriate reset button switch is pressed, the stopped state of the hydraulic supply valve B is released and operation is resumed. Ru. When the contacts of switches S ₄ and S ₅ are up, or when the contacts of switch S ₂ are down, X is grounded. Y is grounded in a dangerous state, and when the supply of hydraulic pressure is stopped, it is connected to ten potential and excites solenoids C ₁ and C ₂ .
Therefore, during normal operation, both solenoids C ₁ and C ₂ are not energized and the lock pins 21 and 22 remain retracted. Relays R _a and R _b are connected to switches S ₁ , S ₃ , S ₄ , and S _{5 ,} so if the valve is in the left position during normal operation, the left limit relay R _a closes, and if it is in the right position, the right limit relay closes. Relay R _b closes. When valve A is on the left, middle, or right, A _l , A _p , and A _r each correspond to "1", and the others correspond to "0". When the switches S ₁ , S ₂ , S ₃ , S ₄ , and S ₅ are in contact with the lower terminals, S=1, and when they are in contact with the upper terminals, S=0. Solenoids C ₁ and C ₂ are set to "1" when energized and "0" when de-energized. Relay R
_a and R _b are "1" when closed. Then we get the following logical formula. S ₁ = A _r (1) S ₂ = A _p (2) S ₃ = A _l (3) X = S ₂ + ₄ + ₅ (4) S ₄ = A _r + ₁ (5) S ₅ = A _l + ₂ (6) C ₁ =Y, R _a (7) C ₂ = Y, R _b (8) R _a ←S ₁ , S ₅ (9) R _b ←S ₃ , S ₄ (10) _a = R _b (11) R _b = R _a (12) Equations (5) and (6) show that if the valve is in the A _r position, the pin 21 will not protrude because the protrusion 11 will be in the way, and the solenoid C ₁ will not be able to protrude. This indicates that the pin 21 will not protrude unless energized. Arrows indicate set/reset operations. When a dangerous condition is detected, the hydraulic pressure supply valve B is stopped and Y=1 at the same time. For X=1, S ₂ =1 or ₄ =1 or ₅ =
It is either 1 or 1. From these formulas, we obtain X=A _p + A _r・Y・R _a + _l・Y・R _b (13). X=1 is a condition for restarting hydraulic pressure. From the first term, it can be said that the stop position is sufficient. From the second term, at the right position (R _a ), the dangerous state (Y=
When 1) is reached, you can see that all you have to do is switch the lever to a position other than the right position (〓). From the third term, it can be seen that if the lever is in a dangerous state (Y=1) when it is in the left position (R _b ), it is sufficient to switch the lever to a position other than the left position ( _l ). Furthermore, when A _r・Y・R _a =1 in the second term,
From equations (5) and (7), S ₄ =0. In other words, lock pin 2
1 protrudes and prevents the lever from being switched to the right position. Similarly, in the third term, when _l・Y・R _b =1,
From equations (6) and (8), S ₅ =0. In other words, lock pin 2
2 protrudes, and the lever cannot be switched to the left position A _l . If a dangerous condition occurs while the lever is at the stop position A _p (Y=1), from (5) to (10), it will not be possible to switch to the position where the lever was located immediately before. Fig. 2 is a circuit diagram when a dangerous state (Y=1) occurs when the control valve is in the right position, and Fig. 3 shows a state in which the lever is switched to stop A _p . Since solenoid _C1 was energized, lock pin 21 protrudes. It is not possible to return it to the right position A _r again. FIG. 4 shows a state in which the lever is further switched to the left position A _l . Solenoid C ₁ , C ₂ , relay R _a , R _b
remains unchanged. FIG. 5 shows the state in which X is grounded and reset by pressing the appropriate reset button. Solenoids C ₁ and C ₂ are demagnetized and lock pins 21 and 22 are retracted. Relay R _a opens and R _b closes. Table 1 is a truth table for a relay coil switch showing the transitions of FIGS. 2-5.

【table】

[Table] On the contrary, if it becomes dangerous when it is in the left position, in Table 1, S ₁ and S ₃ , S ₄ and S ₅ , C ₁ and C ₂ ,
A similar truth table can be obtained by replacing R _a and R _b . The manual directional control valve of the present invention detects a dangerous situation, and after the hydraulic pressure is cut off, the lever must be switched to the opposite direction or to the stop position in order to start supplying hydraulic pressure, and the lock pin must be switched. This prevents them from approaching dangerous situations. The operator does not have to think about which direction is safe, and no operational errors occur. Extremely safe. This is a useful idea.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the hydraulic system, Figures 2 to 5 are circuit diagrams showing the overall configuration of the safety device including the directional control valve A of the present invention, and Figure 2 shows the control valve in the right position. 3 corresponds to a state in which the control valve is switched to the stop position, FIG. 4 corresponds to a state in which it is switched to the left position, and FIG. 5 corresponds to a state in which it is reset. A...Manual directional control valve, B...Hydraulic supply valve,
_S1 to _S5 ...Switch, _C1 , _C2 ...Solenoid,
R _a , R _b ... Relay, A _l ... Left position, A _p ... Stop position, A _r ... Right position, X ... Current line for releasing the stopped state of the hydraulic supply valve, Y ... Current lines 21, 22...Lock pins that connect to positive potential when the hydraulic supply valve stops.

Claims (1)

[Scope of utility model registration request] A manual directional control valve A that can be switched to three positions: right position A _r , stop position A _p , and left position A _l , and three valve position detection switches S that operate individually to detect the position status of the three sides of the valve. ₁ , _S2 , _S3 , first and second lock pins 21, 22 that prevent the valve from moving to the right and left positions, and the respective lock pins 21, 2.
Solenoids C ₁ and C ₂ project 2, and the solenoid closes in a complementary manner depending on the valve position and closes when in a dangerous state.
Self-holding relays R _a and R _b that excite C ₁ and C ₂ ;
The switches S ₄ and S ₅ detect whether the first and second lock pins 21 and 22 are protruding, and in order to restart the hydraulic pressure supply, it is necessary to check whether the lock pins 21 and 22 are protruding or the valve is at the stop position A. With a safety device characterized in that the spool 12 of the control valve is provided with a protrusion 11 that prevents the spool from moving in the opposite direction by engaging with the lock pins 21 and 22 _. Manual directional control valve.