JP3862782B2 - Manually operated switching valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a switching valve that is switched by a manual operation.
[0002]
[Prior art]
Conventionally, as this type of switching valve, a type in which a switching spool is slid to a switching position by a manual operation lever against a return spring that holds a neutral position is generally known. This type of switching valve is used in machines with many manual operations such as construction machinery, but the switching operation force requires more than the total force of the spring force of the return spring and the hydraulic fluid force. If the switching operation is repeated, there is a disadvantage that the operator's fatigue level increases. In order to reduce this degree of fatigue to some extent, the spring force of the return spring is made as weak as possible.
[0003]
[Problems to be solved by the invention]
Even if the return spring is weakened as described above, a switching operation force that is superior to the hydraulic fluid force is necessary. Therefore, as the number of operations increases, the operator's physical fatigue level increases, and the effect of weakening the return spring is very good. Not. If the hydraulic pilot system is used to switch the switching valve with hydraulic pressure, the operating force is reduced, and this problem of fatigue can be solved. There is a drawback that the switching valve cannot be operated due to a failure of the hydraulic pilot system.
[0004]
It is an object of the present invention to provide a manually operated switching valve that can reduce a switching operation force without impairing responsiveness, and can operate the switching valve when necessary regardless of the configuration for reducing the operation force. To do.
[0005]
[Means for Solving the Problems]
According to the present invention, a switching spool is provided in the valve rod so as to be slidable, and a switching valve for switching the switching spool to a switching position against a return spring by a manual operation lever is provided at one end of the switching spool together with the switching spool. A slidable cylinder barrel is connected in the valve rod and two chambers for pressure expansion / contraction are formed between the valve rod and the cylinder barrel, and the cylinder barrel is operated by operating the manual operation lever. A servo spool that engages with the cylinder barrel is connected after sliding within a certain distance, communicated with the pressure chamber from the port formed in the valve rod via the cylinder barrel, and controlled by the servo spool. The above-mentioned object is achieved by providing a control flow path that establishes a fluid pressure that generates thrust in the cylinder barrel in one of the pressure action chambers in the moving direction. When the manual operation lever is switched, the servo spool slides to establish a fluid pressure in one of the pressure working chambers, the fluid pressure applies a thrust to the cylinder barrel, and the switching spool connected to the cylinder barrel is manually operated. It is propelled in the direction of movement of the control lever. This thrust is generated as long as the inclination angle of the manual operation lever is continuously increased. When the operation is stopped, the thrust disappears, and when operated in the reverse direction, the fluid pressure is established in the other pressure working chamber, and the thrust in the reverse direction is generated. It is possible to operate the manual operation lever with a small force. Since the servo spool is engaged with the cylinder barrel, the switching spool can be switched even when the fluid pressure is not established.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The embodiment of the present invention will be described with reference to the drawings. In FIGS. 1 and 2, reference numeral 1 denotes a switching valve that is switched by a manual operation lever 2, and the switching valve 1 includes a pump port 3 and a tank port 4. And a four-port three-position general switching valve in which a switching spool 8 is slidably provided in a valve rod 7 having actuator ports 5 and 6. The switching spool 8 is disposed between retainers 9 and 9 at one end thereof. When the switching spool 8 is slid left and right against the return spring 10, the switching positions 12 and 12 are entered.
[0007]
A substantially cylindrical cylinder barrel 14 is integrally connected to the end of the switching spool 8 opposite to the return spring 10 by a bolt 15 so that the switching spool 8 slides in the valve rod 7. did. Two annular ridges 16, 16 are formed on the outer peripheral surface of the cylinder barrel 14, and these ridges 16 and two protrusions 18, 18 on the inner peripheral surface of the barrel hole 17 of the valve rod 7 Two pressure action chambers 19 and 20 that can expand and contract in the axial direction of the barrel 14 are formed between the valve rod 7 and the cylinder barrel 14. A servo spool 22 having one end connected to the manual operation lever 2 is slidably received in an axial hole 21 inside the cylinder barrel 14, and the other end of the servo spool 22 is connected to the retainers 23, 23 and the return. It was engaged in the spring hole 21 a of the cylinder barrel 14 via a return spring 24 weaker than the spring 10. The axial hole 21 and the spring hole 21 a are separated from each other by the spool land of the servo spool 22. When the manual operation lever 2 is tilted forward and backward , the servo spool 22 slides left and right by a slight gap between the retainers 23 and 23 by bending the return spring 24 .
[0008]
The valve rod 7 is formed with a pilot port 25 connected to an appropriate pilot pressure source (not shown) such as an auxiliary pump, and a drain port 26 connected to a tank. A control flow path 27 formed in the cylinder barrel 14 and the servo spool 22 and communicating with the pressure action chambers 19 and 20 was connected. In the case of FIGS. 1 and 2, the control flow path 27 includes openings 27 a and 27 b extending radially from the pilot port 25 formed in the cylinder barrel 14 into the hole 21, and the pressure working chamber 19 from the hole 21. , 20 extending to 20, an opening 27 e extending from the drain port 26 into the spring hole 21 a, and an opening 27 f extending in the axial direction inside the servo spool 22. The openings 27a and 27b are closed by the land portion 28 when the servo spool 22 is positioned at the neutral position 22a, and open when the servo spool 22 slides from the neutral position 22a.
[0009]
In this case, for example, when the manual operation lever 2 is tilted so that the servo spool 22 enters the cylinder barrel 14 in order to switch the switching valve 1, the servo spool 22 compresses the weak return spring 24. Slide a small distance to the right. One opening 27a is opened by this sliding, and the pressure fluid acts on one pressure action chamber 19 from the pilot port 25, and the other pressure action chamber 20 is connected to the drain port 26. 19 propels the cylinder barrel 14 to the right by the fluid pressure established therein , and this thrust , together with the force of the manual operation lever 2, switches and slides the switching spool 8 connected to the cylinder barrel 14 to the right. If the tilting of the manual operation lever 2 is stopped, the opening 27a of the cylinder barrel 14 that moves to the right is closed, and the flow of the pressure fluid into the pressure working chamber 19 is stopped, so that the movement of the cylinder barrel 14 is also stopped. If the inclination of the manual operation lever 2 is changed in the reverse direction and the servo spool 22 is moved to the left, the fluid pressure is established in the other pressure acting chamber 20, and in this case, the thrust to the left is applied to the cylinder barrel. 14, the leftward operation of the switching spool 8 can be performed with a light force. Even if the fluid pressure cannot be established in the pressure working chambers 19 and 20, if the manual operation lever 2 is operated strongly, the servo spool 22 and the cylinder barrel 14 are engaged, so that the switching spool 8 is slid. Safe to get.
[0010]
The operating force of the manual operation lever 2 in the configuration of FIG. 1 is about 7 to 12 kgf as shown in the hysteresis curve A of FIG. 3, but when the switching spool 8 is directly operated by the manual operation lever 2, FIG. As shown in the hysteresis curve B, a large operating force is required, and the fatigue level of the operator when performing a large number of switching operations can be greatly reduced.
[0011]
In addition, as shown in FIG. 5 or FIG. 6, the control flow path 27 can be of a type in which fluid flows from the pilot port 25 to the drain port 26 via the pressure action chambers 19 and 20, The servo spool 22 and the cylinder barrel 14 are configured to close one flow path to the pressure action chamber 19 or 20 and restrict the other flow path, and establish fluid pressure in one of the required pressure action chambers. Can be made. In addition, if the switching valve 1 is a spool type, the structure of the switching position is arbitrary.
[0012]
【The invention's effect】
As described above, according to the present invention, the cylinder barrel is connected to the switching spool, and two pressure action chambers that can be expanded and contracted are formed between the valve rod and the cylinder barrel. And a servo spool that engages with the barrel is connected, and fluid pressure that is controlled by the barrel and the servo spool to generate thrust in the cylinder barrel in one direction of movement is applied to one of the pressure working chambers. Since the control flow path to be established is provided, the thrust assists the operation force of the manual operation lever, and the manual operation lever can be operated with a small force with good response, and the servo spool is engaged with the cylinder barrel. Even when the fluid pressure is not established, the switching spool can be switched and the safety is high.
[Brief description of the drawings]
FIG. 1 is a cutaway side view showing an embodiment of the present invention. FIG. 2 is a diagram of FIG. 1. FIG. 3 is a diagram of an operation force of a manual operation lever according to the configuration of FIG. FIG. 5 is a diagram of the operation force of the manual operation lever. FIG. 5 is a diagram of another embodiment of the present invention. FIG. 6 is a diagram of still another embodiment of the present invention.
1 switching valve, 2 manual operation lever, 7 valve rod, 8 switching spool, 10 return spring, 14 cylinder barrel, 19/20 pressure working chamber, 22 servo spool, 25/26 port, 27 control flow path,

Claims (2)

A switching spool is provided in the valve rod so as to be slidable, and a switching valve for switching the switching spool to a switching position against a return spring by a manual operation lever. A slidable cylinder barrel is connected, and two pressure action chambers are formed between the valve rod and the cylinder barrel so as to be freely expandable / contractable. After sliding, a servo spool that engages with the cylinder barrel is connected, communicated from the port formed in the valve rod to the pressure acting chamber via the cylinder barrel, and controlled by the servo spool to move in this direction. And a control flow path for establishing a fluid pressure for generating a thrust in the cylinder barrel in one of the pressure action chambers. The valve rod is provided with a pilot port connected to a pilot pressure source and a drain port connected to a tank, the control flow path is controlled by the servo spool, and the two pressure action chambers are connected to the pilot port and the drain port. The manually operated switching valve according to claim 1, wherein the manually operated switching valve is connected to or disconnected from the valve.

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