JPS6227315B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a proportional electromagnetic directional control valve with a manual operation mechanism used in a truck crane or the like.

<Prior art> Conventional examples of proportional electromagnetic directional control valves are disclosed in Japanese Patent Publication No. 47-10751 and Japanese Patent Application Laid-Open No. 50-91037, but these proportional electromagnetic directional control valves are is also controlled only by electrical signals. However, truck cranes, aerial work vehicles, power shovels, etc. that use proportional electromagnetic directional control valves often require a manual operation mechanism. For example, for loading and unloading small amounts of cargo using a truck crane, starting and finishing work using an aerial work vehicle, and working in non-dangerous areas using a power shovel, manual operation is better than using electrical signals. It is often convenient. Furthermore, in the event of an electrical system failure, a manual operating mechanism becomes indispensable in any case.
The above-mentioned Japanese Patent Publication No. 47-10751 and Japanese Patent Application Laid-Open No. 50-91037 did not have a manual operation mechanism, so they had many disadvantages in use.

For the above reasons, proportional solenoid directional control valves with a manual operation mechanism have been proposed, such as the
-50153 is disclosed. Below, FIG. 4 showing this directional control valve will be described.

First, a hole 119 is arranged concentrically with respect to the main spool 113, and a hollow adjusting member 114 is slidably guided in the hole 119 in a liquid-tight manner.
1. It is fixedly connected to the main spool 113 in the axial direction by a leaf spring 122 and a separating ring 123. An O-ring 124 between the pin 121 and the adjusting member 114 has a sealing effect and allows the adjusting member 114 to be slightly off-centered relative to the main spool 113. The other end of the adjusting element 114 receives a double-acting return device 125, the return spring 126 of which is connected via two spring receivers 127 to the adjusting element 114 on the one hand and to the pilot spool 128 on the other hand. The portion of the pilot spool 128 protruding from the valve casing 129 is supported by the hollow adjusting member 11.
It's now within 4. pilot spool 128
has a smaller diameter than the diameter of the main spool 113, so the adjusting member 114
1, and the small effective surface of this differential piston 131 is connected to the casing 118 and the switching valve casing 11.
1 and a large effective surface is assigned to a second pressure chamber 133 between the housing 118 and the valve housing 129.

The precontrol valve 116 is configured as a 3-port 3-position switching valve, and has a first port 134, a second port 134, and a second port 134.
135 and a third port 136, these ports are connected to the pilot spool 12.
8 are separated from each other when they are in the neutral position in the figure. The first port 134 communicates with the first pressure chamber 132 via holes 137 and 138 in the casing 118, and communicates with the inflow passage 139 in the switching valve casing 111 via the hole 138. The second port 135 of the precontrol valve 116 is connected to the second port 135 of the precontrol valve 116.
The third port 136 is communicated with a return passage 142 in the switching valve casing 111 via a hole 141 in the casing 118. pilot spool 128
The collar defines a first control edge 143 and a second control edge 144, which control edges contact the first port 134 when the pilot spool 128 is displaced from the central neutral position to the working position. Second
135 and communication between the second port 135 and the third port 136.

An electromagnetic drive 117 is arranged in the housing 129 of the precontrol valve 116 on the side opposite the piston part 115 , the electromagnet 145 of which has two armatures 146 , 147 fixed on the pilot spool 128 . are doing. Electromagnet 145
An amplification stage 148 is arranged above the amplifier stage 148, the input terminal 149 of which can be connected to a potentiometer (not shown) for providing a setpoint value. The potentiometer may alternatively be an inductive generator or an electronic controller. Electromagnet 14
5, the force acting on the armatures 146, 147 is always proportional to the current.

Next, the operation of the above-mentioned directional control valve will be explained.

When no signal is applied to input terminal 149, pilot spool 128 is in the neutral position shown, in which pilot spool 1
28 is centered by hydraulic forces.

When a signal is applied to the input terminal 149, the armature 1
46 is pulled toward the right side with a force proportional to the amount of current applied. At this time, the armature 146 carries the pilot spool 128 and the pressure chamber 1
Communication between 32 and 133 is provided by a first control edge 143. As a result, the pressure in the second pressure chamber 133 increases and pushes the differential piston 131 to the left, and the leftward movement of the differential piston 131 causes the return spring 126 to bend and the armature to move. 146 is applied to the pilot spool 128 to return the pilot spool 128 to the neutral position.
When the pilot spool 128 is returned to the neutral position by this spring force, the pressure chambers 132 and 1
33 is cut off. In this way, the force acting on the armature 146 is converted via the return spring 126 into a distance of movement in the adjustment member 114, which actuates the main spool 113.

As the force acting on the armature 146 increases further, the process is repeated until a balance of forces in the neutral position is again established on the pilot spool 128, in which case the adjustment member 114 exerts an even greater force in proportion to the greater amount of current. .

When the force acting on armature 146 decreases when differential piston 131 is in the offset position, return spring 126 pushes pilot spool 128 toward the left. The second pressure chamber 133 is located at the second control edge 1
44 to third port 136, return passage 142
Pressure is released inward. The control pressure in the first pressure chamber 132 causes the differential piston 131 to move toward the right side,
This causes the forces of return spring 126 and armature 146 to be rebalanced at the neutral position of pilot spool 128. In this case, the adjustment member 11
4 is also proportional to the amount of current applied to input terminal 149.

<Problems to be Solved by the Invention> The switching valve 112 also has a manual operating device (not shown) on the opposite side of the adjusting device 110. This allows the main spool 113 to be manually operated in an emergency such as when the supply of pressure fluid (pilot pressure fluid) to the first and second pressure chambers 132, 133 is cut off. However, when the main spool 113 is shifted towards the right by the manual operating device, pressure fluid must be forced out of the second pressure chamber 133. For this purpose, a check valve 15 is provided between the second pressure chamber 133 and the first port 134.
1 is placed. Also, main spool 113
When the pilot spool 128 is shifted to the left by the manual operation device, the resilient force of the spring 126 shifts the pilot spool 128 to the left, connecting the second port 135 and the third port 136, This is done by supplying fluid to the pressure chamber 133.

As described above, this manually operated directional switching valve is equipped with a manual operating device at one end of the switching valve casing 111, and when the main spool 113 is operated by this manual operating device, the operating piston 131 is actuated. The first and second pressure chambers 132,1
When supplying and discharging fluid to and from 33, the pre-control valve 11
6, a large operating force is required, and furthermore, the first and second pressure chambers 1
If fluid pressure is acting on 32, 133,
Since the pressing force from the pilot hydraulic pressure acts on the actuating piston 131, there are problems such as manual operation being impossible.

The object of the present invention is to enable operation with the same operating force as a manually operated directional control valve, regardless of the presence or absence of pilot pressure fluid.

<Means for solving the problems> In order to solve the above problems, the means of the present invention are as follows:
A directional control valve having a spool is provided with a manual operation part at one end and an operation cylinder part at the other end,
This operation cylinder section is formed by a piston connected to the spool, an inner hole into which the piston is slidably inserted, and pilot pressure chambers provided on both sides of the inner hole to which a pilot source is connected. In the directional control valve configured to control the pilot hydraulic pressure to the pilot pressure chamber by a solenoid valve, the pilot pressure chamber is provided with a return spring for pilot operation, and the return spring for pilot operation The piston is in contact with the spool when the manual operation section switches the spool, and the solenoid valve is configured to connect the pilot pressure chamber and the tank during demagnetization.

<Function> In the present invention having the above-mentioned means, the pressure oil in the pilot pressure chamber is connected to the tank when no actuation command is given to the solenoid valve. At this time, when the spool is operated by the manual operation part, the piston connected to the spool is moved from one side to the other, but at this time, the pressure oil in the pilot pressure chamber is flowed out to the tank via the solenoid valve. Since the return spring for pilot operation comes into contact with the piston when the spool is switched, manual operation with a small operating force is possible regardless of whether or not pilot pressure oil is supplied to the pilot pressure chamber. It is what it is.

EMBODIMENT OF THE INVENTION Hereinafter, the proportional electromagnetic directional control valve with a manual operation mechanism of this invention will be explained in detail based on drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention, in which an operating cylinder section 1 has its tip fixed to a main spool 2 of a directional control valve 2a inserted from one end of the operating cylinder section 1. It includes a main spool connecting member 3. The main spool connecting member 3 passes through a through hole 5 provided in the operating cylinder body 4, is slidably supported by the operating cylinder body 4 through the through hole 5, and is coaxially connected to the main spool 2. It can be interlocked in the axial direction. A piston fitting portion 6 is provided approximately at the center of the main spool connecting member 3 by making the connecting member 3 small in diameter, and the piston fitting portion 6 is slidably fitted into the inner hole 6a. Two pistons 7a and 7b are slidably fitted together, and an intermediate chamber 8 is formed between the pistons 7a and 7b. Pilot pressure chambers 9a and 9b are formed on the opposite side of this intermediate chamber 8, respectively.
Return springs 10a, 10b for controlling the pilot pressure are tensioned inside the pilot pressure chambers 9a, 9b. The pilot pressure operation return spring 10a,
10b presses the pistons 7a and 7b;
It is stretched between the pilot operating return spring receivers 11a, 11b that slide along the inner wall of the operating cylinder portion 1 and the operating cylinder body 4. A neutral position return device 13a of a manual operation section 15a (see FIGS. 2 and 3) is connected to the operation cylinder section 1 at the tip of the main spool connection member 3 opposite to the side connected to the main spool 2. It has been set up. A return spring 13 for manual lever operation is placed in the return chamber 12 of this neutral position return device 13a, and a return spring receiver 14a for manual lever operation is in contact with the inner wall of the return chamber 12 for manual lever operation when the main spool 2 is in the neutral position. ，
It is stretched so as to press 14b. When the main spool 2 moves, one of the manual lever operating return spring receivers 14a and 14b that receives the manual lever operating return spring 13 moves integrally with the main spool connecting member 3,
The other one is installed so that the main spool 2 is in contact with the inner wall of the return chamber 12 for manual lever operation while remaining in the neutral position, and when the main spool 2 moves from the neutral position in this way, i.e. When the main spool connecting member 3 moves from the neutral position, the manual lever operation return spring 13 is compressed between the manual lever operation return spring receivers 14a and 14b, and is expanded by the spring pressure when returning to the neutral position. It's getting old.

On the other hand, a manual lever 15 is provided on the opposite side of the main spool 2 to the connection side with the main spool connection member 3.
(See Figures 2 and 3), and by operating the manual lever 15, the main spool 2 and the main spool connecting member 3 are moved from the neutral position in the axial direction of the main spool 2 (in the arrow E or F direction). By this movement, the main spool 2 acts as a directional control valve for an actuator (not shown), and for example, as shown in FIG. Port A led,
In a directional control valve having port B and port T leading to a tank (not shown), by moving the main spool 2 from the neutral position in the direction of arrow E, the passage from port P to port A and from port B to port T is established. By moving the main spool 2 from the neutral position in the direction of arrow F, the passages from port P to port B and from port A to port T are opened, and the passages with port P are opened. The oil is now flowing into the cylinder on the side that is exposed.

Next, the pre-control valve 16 whose load is the operation cylinder section 1, that is, the main spool 2, will be explained.
The precontrol valve 16 is configured as a 3-port, 3-position switching valve. First, pilot passages 16a and 16b, which are passages for pilot fluid supplied from a pilot source 16', have a fixed throttle 17 in the middle.
a, 17b are provided, and the fixed aperture 17
The downstream side of a and 17b are solenoids 28a and 28b.
and a pilot pressure control valve 18 consisting of conical pilot valves 18a and 18b, respectively.
It is led to the pilot pressure chambers 9a, 9b via the pilot spool return spring chambers 19a, 19b on the downstream side of the fixed throttles 17a, 17b, so that the pilot pressure chamber 9a, the pilot spool return spring chamber 19a, and the pilot pressure The chamber 9b and the pilot spool return spring chamber 19b are always at the same pressure, and the pilot spool 20 slides against the pressing force of the pilot spool return springs 21a, 21b stretched in the pilot spool return spring chambers 19a, 19b. It is set up internally. As mentioned above, this pre-control valve 16 has three ports, and port 2 is located in the middle of the three ports.
2 is led to the intermediate chamber 8, one port 23 of the ports at both ends is connected to the pilot source 16' through the pilot passage 16b, and the other port 24 is connected to the pilot source 16' through the pilot passage 16b.
is led to a tank (not shown) via a tank passage 25. These ports are pilot valve 20
When the pilot spool 20 of A is in the neutral position, the pilot pressure fluid from the pilot source 16' is blocked by the pilot spool 20, and the intermediate chamber 8 and the tank are connected. Said pilot spool return spring 2
1a and 21b are pilot spool return spring chamber 1
The pilot spool 20, which is stretched between the spring receivers 26a, 26b which are in contact with the pilot spool 20 at 9a, 19b, and the inner wall of the pilot spool return spring chamber 19a, is held neutrally.

The pilot valves 18a, 18b are located at valve seats 27a, 2 at the open ends of the pilot passages 16a, 16b.
7b, and furthermore, the pilot valve 18
a, 18b are movable iron cores 29a, 29 of solenoids 28a, 28b provided outside the pre-control valve 16;
When a voltage is applied to the power source of the solenoid 28a or 28b, the valve seat 27a or 27b is pressed against the valve seat 27a or 27b with a force proportional to the magnitude of the voltage.

Next, the operation of the proportional electromagnetic directional control valve with a manual operation mechanism configured as described above will be explained.

First, let's talk about operating the main spool 2 with the manual lever 15. For example, if you want to open a passage from port P to port A, operate the manual lever 15 and move the main spool 2 in the direction of arrow E. Just move it.

During manual operation, neither of the solenoids 28a and 28b are energized, so the pilot valve 18
a, 18b are not pressed against the valve seats 27a, 27b, and are not pressed against the pilot spool return spring chambers 19a, 19b and the pilot pressure chambers 9a, 9.
Both b are tank pressure. When both the pilot spool return spring chambers 19a and 19b are at tank pressure, the pilot spool 20 is held neutrally by the pilot spool return springs 21a and 21b. The port 22 communicating with the chamber 8 and the port 24 communicating with the tank passage 25 are in an open state, so that the intermediate chamber 8 is also at tank pressure. Therefore, when the main spool 2 is moved by the manual lever 15, the pistons 7a and 7b can freely move toward the intermediate chamber 8 so as to contract the intermediate chamber 8. When the spool 2 is moved in the direction of the arrow E, the piston 7b moves in the E direction along with the main spool connecting member 3 interlocking with the main spool 2, as shown in FIG. It is sent to a tank (not shown) through a tank passage 25. Further, when the main spool connecting member 3 moves in the E direction in conjunction with the main spool 2, the manual lever operating return spring receiver 14b follows the main spool connecting member 3 in the manual lever operating return chamber 12.
The return spring 13 for manual spring operation is compressed. As is clear from the above, when the main spool 2 is moved in the E direction by operating the manual lever 15, the piston 7b similarly moves in the E direction, and until it comes into contact with the piston 7a, the main spool 2 is moved only against the repulsive force of the manual lever operation return spring 13. However, if the distance Xa until the manual lever operation return spring receivers 14a, 14b come into contact is larger than the distance Ya until the pistons 7a, 7b come into contact, the pistons 7a,
Since the main spool 2 is operated by the manual lever 15, it is desirable that Xa=Ya since the main spool 2 is operated by the manual lever 15 since after the contact of the main spool 7b, the repulsive force of the return spring 10a for pilot pressure operation is also applied. When the main spool 2, which has been moved in the direction of the arrow E as described above, is released from the manual lever 15, it returns to the neutral position by the repulsive force of the manual lever operation return spring 13.

The operation when the main spool 2 is moved in the direction of the arrow F by the manual lever 15 is the same as the operation when the main spool 2 is moved in the direction of the arrow E described above, so a description thereof will be omitted.

Next, the electromagnetic operation of moving the main spool 2 and the pre-control valve 16 will be explained.

Now, when a voltage is applied to the solenoid 28b, the pilot valve 18b attached to the movable iron core 29b is pressed against the valve seat portion 27b with a force corresponding to the applied voltage. Therefore, the pressures in the pilot spool return spring chamber 19b and the pilot pressure chamber 9b located downstream of the fixed throttle 17b also increase in proportion to the force with which the pilot valve 18b is pressed against the valve seat portion 27b. On the other hand, since no voltage is applied to the solenoid 28a, the pilot valve 18a is closed to the valve seat 27a.
is not pressed down, and the fluid in the pilot spool return spring chamber 19a and the pilot pressure chamber 9a is freely sent out to the tank passage 25. Here, if the pressing force of the pilot spool return springs 21a and 21b is set to be sufficiently small, the pilot spool 20 will be activated when voltage is applied to the solenoid 28b and the pressure in the pilot spool return spring chamber 19b begins to increase. Since the pressure balance between the return spring chamber 19a, the pilot pressure chamber 9a, the pilot spool return spring chamber 19b, and the pilot pressure chamber is disrupted, the pilot spool moves toward the return spring chamber 19a, and at this time, the intermediate chamber 8 as shown in FIG. The port 22 leading to the tank passage 25 and the port 24 leading to the tank passage 25 are blocked, while the port 22 leading to the intermediate chamber 8 and the port 24 leading to the pilot source 1
The port 23 leading to 6' becomes open. Therefore, the intermediate chamber 8 changes from the tank pressure when the pilot spool 20 is in the neutral position to the original pressure of the pilot source 16', and the pistons 7a, 7b are pressed against both ends of the piston fitting portion 6. The pistons 7a and 7b, which are pressed against both ends of the piston fitting part 6 and form the intermediate chamber 8 between them, are connected to the solenoid 28b.
The main spool connecting member 3 moves toward the pilot pressure chamber 9a (in the direction of arrow E in the figure) due to the pilot control pressure applied to the pilot pressure chamber 9b by applying a voltage to the main spool 2. Move in the direction of arrow E in the figure. Since the pilot control pressure applied to the pilot pressure chamber 9b passes through the fixed throttle 17b, the pilot control pressure applied to the intermediate chamber 8
Therefore, even when the pilot control pressure is applied to the pilot pressure chamber 9b and the pistons 7a, 7b move in the direction of arrow E in the figure, the pistons 7a, 7b remain in the piston fitting portion 6.
It moves as one while being pressed against both ends. Here, the pistons 7a and 7b move against the combined spring force of the pilot pressure operation return spring 10a and the manual lever operation return spring 13, and therefore the moving distance of the pistons 7a and 7b is the same as that of the pilot pressure chamber 9b. The pilot pressure operating return spring 10
This is the distance to the position where the combined spring force of a and the manual lever operation return spring 13 are balanced. At this time,
As is clear from the above description, main spool 2
It can be seen that the main spool 2 moves the same distance as the pistons 7a and 7b, and thus the main spool 2 is controlled in proportion to the pilot control pressure applied to the pilot pressure chamber 9b, that is, the applied voltage applied to the solenoid 28b.

When voltage is applied only to the solenoid 28a, the main spool 2 moves in the direction of arrow F in the figure.
Since this is similar to the case where a voltage is applied only to 8b and the main spool 2 moves in the direction of arrow E in the figure, the explanation will be omitted.

When the main spool 2 moves, a sliding resistance force due to the seal 30 to maintain liquid tightness and a fluid force due to the flow of oil from the directional control valve in the directions of arrows X and Y in the figure, for example, act on the main spool 2. Although it causes an error in the positioning of the main spool 2, the return springs 10a, 1 for pilot pressure operation
The spring constant of 0b is increased to increase the combined spring force with the manual lever operation return spring 13 to overcome the sliding resistance force due to the seal 30 and the fluid force due to the oil of the directional control valve. As a result, errors in positioning the main spool 2 can be suppressed within a practically acceptable range.

<Effects of the Invention> As explained above, according to the present invention, when no operation command is applied to the solenoid valve, the pilot pressure chamber communicates with the tank via the solenoid valve, and the operation cylinder The piston of
Within the switching range of the spool, the spool can be moved freely regardless of the return spring for pilot operation, so there is no resistance to manual operation. Therefore, it can be operated with the same feeling as a normal manually operated valve.
Further, the manual operation described above is the same even when pilot pressure oil is supplied to the pilot pressure chamber. Therefore, switching between electromagnetic operation and manual operation can be performed arbitrarily. Furthermore, since the spring force of the return spring for pilot operation is not related to manual operation,
It can be made stronger if necessary. If the pilot oil pressure is strengthened in accordance with the spring force of this pilot operation return spring, the spool will be operated with a large force acting on it, which has the effect of reducing the effects of disturbances (particularly flow force) acting on the spool. has.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing an embodiment of the present invention, Fig. 2 is a cross-sectional explanatory view when manual operation is performed, and Fig. 3 is a cross-sectional view when electromagnetic operation is performed using a pre-control valve. FIG. 4 is a sectional view of a conventional proportional electromagnetic directional control valve with a manual operation mechanism. DESCRIPTION OF SYMBOLS 1... Operation cylinder part, 2... Main spool (spool), 6a... Inner hole, 7a, 7b... Piston, 9a, 9b... Pilot pressure chamber, 10
a, 10b...Return spring for pilot pressure operation, 1
5a...Manual operation section, 16'...Pilot source,
18...Pilot pressure control valve (electromagnetic valve).

Claims (1)

[Claims] 1 A manual operation section is provided at one end in the direction of the spool, and an operation cylinder section is provided at the other end, and the operation cylinder section includes a piston connected to the spool and an inner part into which the piston is slidably fitted. The directional control valve has a hole and a pilot pressure chamber provided on both sides of the inner hole and connected to a pilot source, and is configured to control the pilot hydraulic pressure to the pilot pressure chamber by a solenoid valve. The pilot pressure chamber is provided with a return spring for pilot operation, and the return spring for pilot operation and the piston are operated by the manual operation section.
A proportional solenoid directional control valve with a manual operation mechanism, wherein the solenoid valve is in contact with the spool when the spool is switched, and the solenoid valve connects the pilot pressure chamber and the tank when demagnetized.