JP4873934B2 - Cylinder lowering prevention valve device - Google Patents

Description

  The present invention relates to a cylinder lowering prevention valve device that prevents a cylinder from lowering due to the action of its load.

As this type of cylinder lowering prevention valve device, the invention described in Patent Document 1 has been conventionally known. This conventional device will be described with reference to FIG. The conventional apparatus, the valve body B, a supply passage 2 communicating with the pump P through the check valve 1, a pair of actuator ports 3 and 4, to form a return passage (5, 6) communicating with the tank Yes. The actuator port 3 of hand communicates with the head side chamber of the cylinder C, the other actuator port 4 is communicated with the rod side chamber.

Further, the main spool MS is incorporated in the valve body B, but both ends of the main spool MS face the main pilot chambers 7 and 8. The main pilot chambers 7 and 8 are connected to a proportional valve 9 so that pressure corresponding to the operation amount of the proportional valve 9 is guided to the main pilot chambers 7 and 8. In the figure, reference numeral 10 denotes a centering spring provided in one main pilot chamber 7 . The action of cell pointer ring spring 10, when the main spool MS is in the neutral position shown, the state actuator port 3 and 4, which are cut off the communication to any of the supply passage 2 and the return passages 5,6 Keep.

  When the main spool MS moves in the right direction in the drawing, one actuator port 3 and the supply passage 2 communicate with each other through the first annular groove 11 formed in the spool, and the other through the second annular groove 12. The actuator port 4 and the return passage 6 communicate with each other. When the main spool MS moves in the left direction of the drawing, the other actuator port 4 and the supply passage 2 communicate with each other via the second annular groove 12 and one actuator is connected via the first annular groove 11. The port 3 communicates with the return passage 5.

The actuator port 3 of hand is provided with a main poppet MP, the boundary of the main poppet MP, the actuator port 3, are divided into a spool side 3a and the actuator side 3b. The main poppet MP configured as described above has one side facing the back pressure chamber 13, and the back pressure chamber 13 is provided with a pilot poppet PV, and the back surfaces of the main poppet MP and the pilot poppet PV are connected to each other. Are facing each other. A spring 14 is interposed between the opposing portions of the main poppet MP and the pilot poppet PV.

Main import pets MP is the action of the spring 14, normally pressed against the seat portion 15 formed in the valve body B side to cut off the spool side 3a of the actuator port 3 and the actuator side 3b. Further, the main poppet MP is formed with a through hole 16 that is always in communication with the actuator side 3b of the actuator port 3, and this through hole 16 is always in communication with the back pressure chamber 13 through the orifice 17. Yes. Also, the pilot poppet PV is normally pressed against the seat portion 18 by the action of the spring 14 to block communication between the back pressure chamber 13 and the drain port 19.

Therefore, when the cylinder C to the load W is applied, if the main spool MS is in the neutral position shown, towards the actuator side 3b than spool side 3a becomes high. Since the high pressure on the actuator side 3b is guided to the back pressure chamber 13, the main poppet MP and the pilot poppet PV are firmly pressed against the seat portions 15 and 18. As a result, the load on the cylinder C is maintained and its drop is prevented.

It is provided with the pilot piston PP opposite the path for the pilot poppet PV, and to face the outside of the pilot piston PP to the pilot chamber 20. The spring force of the spring 21 is applied to the inside of the pilot piston PP, that is, the side opposite to the pilot chamber 20.

Therefore, as long as the pilot pressure does not act on the pilot chamber 20, the push rod 22 of the pilot piston PP is, thus keeping the position away from the pilot poppet PV by the action of the scan pulling 21. In other words, unless the pilot pressure is applied to the pilot chamber 20, the pilot poppet PV is pressed against the seat portion 18 to block communication between the back pressure chamber 13 and the drain port 19. Incidentally, pilot chamber 20, as the other main pilot chamber 8 common pilot pressure is guided, is connected to the proportional valve 9.

  Now, when the proportional valve 9 is operated so as to guide the pilot pressure to one main pilot chamber 7, the other main pilot chamber 8 and pilot chamber 20 communicate with the tank. As described above, when the pilot pressure is introduced into one of the main pilot chambers 7, the main spool MS moves in the right direction in the drawing. By the rightward movement of the main spool MS, the supply passage 2 and the actuator port 3 communicate with each other through the first annular groove 11. The actuator port 4 and the return passage 6 communicate with each other through the second annular groove 12.

Therefore, in the actuator port 3, the pressure on the spool side 3a is higher than the pressure on the actuator side 3b , so that the main poppet MP is forcibly pushed open, and the pressure fluid supplied from the supply passage 2 is supplied to the head of the cylinder C. Supplied to the side chamber. Further, since the rod side chamber of the cylinder C communicates with the return passage 6 via the actuator port 4, the cylinder C increases the load w.

From this state, if the proportional valve 9 is operated to remove the pressure in the main pilot chamber 7, the main spool MS returns to the neutral position shown in the figure by the action of the centering spring 10. In this neutral position, the actuator side 3b has a higher pressure than the spool side 3a of the actuator port 3 by the load w, so that the main poppet MP seats the seat portion 15 firmly. Therefore, the lowering of the cylinder C is prevented by the function of the main poppet MP.

  When the proportional valve 9 is operated from the neutral state to guide the pilot pressure to the other main pilot chamber 8 and the pilot chamber 20, and the one main pilot chamber 7 is communicated with the tank, the main spool MS is shown in the drawing. Simultaneously with the movement to the left, the pilot piston PP also moves against the spring 21. As the pilot piston PP moves, the push rod 22 pushes the pilot poppet PV open.

When the pilot poppet PV is opened, the back pressure chamber 13 communicates with the drain port 19, so that a flow is generated in the orifice 17 of the main poppet MP, and a pressure difference is generated before and after that. This pressure difference opens the main poppet MP. That is, the main poppet MP has a larger diameter on the back pressure chamber 13 side than the diameter of the seat portion 15, and when the pressure in the actuator side 3 b is higher than that in the back pressure chamber 13, Poppet MP will open. At the same time, since the main spool MS is also moved leftward in the drawing, the supply passage 2 and the actuator port 4 communicate with each other via the second annular groove 12 and the actuator port 3 via the first annular groove 11. And the return passage 5 communicate with each other. Accordingly, the fluid in the head side chamber of the cylinder C is returned to the tank via the actuator side 3 b of the actuator port 3 → the spool side 3 a → the first annular groove 11 → the return passage 5.

However, in this case, the main poppet MP is opened before the notch 23 formed at the edge of the first annular groove 11 communicates with the return passage 5 for the following reason. For example, when the main poppet MP is opened after the notch 23 is opened, the return flow rate from the cylinder C flows into the notch 23 at the instant when the main poppet MP is opened. However, the notch 23 is used for inching control while slightly changing the communication opening degree between the actuator port 3 and the return passage 5. If the return flow rate flows into the notch 23 having such a function at once, it is difficult to perform the delicate inching control. Therefore, as described above, the main poppet MP is opened first, and after returning to the spool side 3a of the actuator port 3 to reach the flow rate, the notch 23 is opened so that accurate inching control can be performed. Yes.
JP-A-9-126202

  In the conventional cylinder descent prevention valve device as described above, when the pilot poppet PV opens the seat portion 18, the back pressure chamber 13 communicates with the drain port 19, so the pressure in the back pressure chamber 13 decreases at a stretch. End up. When the pressure in the back pressure chamber 13 decreases at a stretch in this way, the main poppet MP retreats vigorously and collides with other members at the stroke end, but a collision sound is generated at this time. There is a problem that the collision sound is recognized as an abnormal sound by an operator or the like.

  An object of the present invention is to provide a cylinder lowering prevention valve device that does not generate a collision noise of a main poppet.

This invention comprises a main spool that incorporates slidably in the valve body, a pair of main pilot chamber to face the ends of the main spool, an actuator port formed in the server Rububodi, a cylinder connected to the actuator port , formed in the valve body, and a supply passage communicating with the actuator port via an annular groove formed in the main spool when the main spool is moved in one direction, the ring when the main spool is moved in the other direction a return passage communicating with the actuator port via the shaped groove, a main poppet provided in the passage process of connecting the ring-shaped groove and the actuator port, a back pressure chamber for guiding the load pressure of the actuator causes faces the main poppet A pilot poppet to open and close this back pressure chamber A pilot piston for push open the lot poppet, in the cylinder drop valve device provided with a pilot chamber for guiding the pilot pressure to act on the pilot piston, when the path for the pilot poppet is opened, the back pressure chamber, the actuator ports When the return flow is provided with a discharge passage that communicates with the actuator port downstream of the main poppet, and when the pilot poppet is closed, the back pressure chamber communicates with the actuator port, and the pilot poppet opens. , the annular groove of Rutotomoni main spool is provided an opening and closing valve portion to block the communication between the actuator port to be upstream of the back pressure chamber and the main poppet to the pilot poppet, in that to form a notch that communicates with the return passage Has characteristics.

According to the first invention, when the pilot poppet is opened, against the return flow of the actuator ports, since communicated to the back pressure chamber to the actuator port to which the downstream side of the main poppet, a back pressure chamber the working fluid Is returned to the tank via the valve body B. Therefore, compared with the conventional case where the working fluid in the back pressure chamber is directly discharged from the drain port, the flow path from the back pressure chamber to the tank is longer in the present invention. Since the flow path is long and the main spool has a notch in this way, pressure loss occurs, the pressure in the back pressure chamber does not drop rapidly, and the main poppet also moves back slowly. Therefore, the impact sound of the main poppet is not generated.

  The greatest feature of this embodiment is that when the pilot poppet PV is opened, the back pressure chamber 13 is provided on the actuator port 3 on the downstream side of the main poppet MP, that is, on the spool side 3a with respect to the return flow of the actuator port 3. This is a point where a discharge passage 24 for communication is provided. And in this embodiment, it replaced with the conventional drain port 19, and provided the discharge channel | path 24, and the whole is demonstrated in detail below also including the part which overlaps with the past.

Embodiment of the invention shown in Figure 1, the valve body B, a supply passage 2 communicating with the pump P through the check valve 1, a pair of actuator ports 3 and 4, the return path 5 communicating with the tank, 6 is formed. The actuator port 3 of hand communicates with the head side chamber of the cylinder C, the other actuator port 4 is communicated with the rod side chamber.

Further, the main spool MS is incorporated in the valve body B, but both ends of the main spool MS face the main pilot chambers 7 and 8. The main pilot chambers 7 and 8 are connected to a proportional valve 9 so that pressure corresponding to the operation amount of the proportional valve 9 is guided to the main pilot chambers 7 and 8. In the figure, reference numeral 10 denotes a centering spring provided in one main pilot chamber 7 . The action of cell pointer ring spring 10, when the main spool MS is in the neutral position shown, the state actuator port 3 and 4, which are cut off the communication to any of the supply passage 2 and the return passages 5,6 Keep.

  When the main spool MS moves in the right direction in the drawing, one actuator port 3 and the supply passage 2 communicate with each other through the first annular groove 11 formed in the spool, and the other through the second annular groove 12. The actuator port 4 and the return passage 6 communicate with each other. When the main spool MS moves in the left direction of the drawing, the other actuator port 4 and the supply passage 2 communicate with each other via the second annular groove 12 and one actuator is connected via the first annular groove 11. The port 3 communicates with the return passage 5.

The actuator port 3 of hand is provided with a main poppet MP, the boundary of the main poppet MP, the actuator port 3, are divided into a spool side 3a and the actuator side 3b. The main poppet MP configured as described above has one side facing the back pressure chamber 13, and the back pressure chamber 13 is provided with a pilot poppet PV, and the back surfaces of the main poppet MP and the pilot poppet PV are connected to each other. Are facing each other. A spring 14 is interposed between the opposing portions of the main poppet MP and the pilot poppet PV.

Main import pets MP is the action of the spring 14, normally pressed against the seat portion 15 formed in the valve body B side to cut off the spool side 3a of the actuator port 3 and the actuator side 3b. Further, the pilot poppet PV is normally pressed against the seat portion 18 by the action of the spring 14 and closes the seat portion 18. The pilot poppet P V which thus is provided with a through hole 16 is a movable valve of the present invention. The through-hole 16 is opened when the pilot poppet P V is closing the seat portion 18 to communicate the back pressure chamber 13 with the actuator side 3b of the actuator port 3 upstream of the main poppet MP . . Further, when the pilot poppet P V opens the seat portion 18, the valve is closed to block communication between the back pressure chamber 13 and the actuator side 3 b of the actuator port 3.

Further, when the sheet over isolation portion 18 is opened, it is provided discharge passage 24 communicating the spool side 3a of the back pressure chamber 13 and the actuator port 3. In other words, when the pilot poppet PV is opened, the discharge passage 24 moves the back pressure chamber 13 to the spool side 3a of the actuator port 3 that is downstream of the main poppet MP with respect to the return flow of the actuator port 3. Communicate.

Incidentally, when the cylinder C to the load W is applied, if the main spool MS is in the neutral position shown, towards the actuator side 3b than spool side 3a becomes high. At this time, the pilot poppet PV is closed and the through hole 16 is kept open. Therefore, the high pressure on the actuator side 3b is guided to the back pressure chamber 13 through the open through hole 16, and the main poppet MP and the pilot poppet PV are firmly pressed against the seat portions 15 and 18. As a result, the load on the cylinder C is maintained and its drop is prevented.

It is provided with the pilot piston PP opposite the path for the pilot poppet PV, and to face the outside of the pilot piston PP to the pilot chamber 20. The spring force of the spring 21 is applied to the inside of the pilot piston PP, that is, the side opposite to the pilot chamber 20.

Therefore, as long as the pilot pressure does not act on the pilot chamber 20, the push rod 22 of the pilot piston PP is, thus keeping the position away from the pilot poppet PV by the action of the scan pulling 21. In other words, unless the pilot pressure is applied to the pilot chamber 20, the pilot poppet PV is pressed against the seat portion 18 to block communication between the back pressure chamber 13 and the discharge passage 24 . Incidentally, pilot chamber 20, as the other main pilot chamber 8 common pilot pressure is guided, is connected to the proportional valve 9.

  Now, when the proportional valve 9 is operated so as to guide the pilot pressure to one main pilot chamber 7, the other main pilot chamber 8 and pilot chamber 20 communicate with the tank. As described above, when the pilot pressure is introduced into one of the main pilot chambers 7, the main spool MS moves in the right direction in the drawing. By the rightward movement of the main spool MS, the supply passage 2 and the actuator port 3 communicate with each other through the first annular groove 11. The actuator port 4 and the return passage 6 communicate with each other through the second annular groove 12.

Therefore, in the actuator port 3, the pressure on the spool side 3a is higher than the pressure on the actuator side 3b , so that the main poppet MP is forcibly pushed open, and the pressure fluid supplied from the supply passage 2 is supplied to the head of the cylinder C. Supplied to the side chamber. Further, since the rod side chamber of the cylinder C communicates with the return passage 6 via the actuator port 4, the cylinder C increases the load W.

From this state, if the proportional valve 9 is operated to remove the pressure in the main pilot chamber 7, the main spool MS returns to the neutral position shown in the figure by the action of the centering spring 10. In this neutral position, the actuator side 3b has a higher pressure than the spool side 3a of the actuator port 3 by the load W, so that the main poppet MP seats the seat portion 15 firmly. Therefore, the lowering of the cylinder C is prevented by the function of the main poppet MP.

  When the proportional valve 9 is operated from the neutral state to guide the pilot pressure to the other main pilot chamber 8 and the pilot chamber 20, and the one main pilot chamber 7 is communicated with the tank, the main spool MS is shown in the drawing. Simultaneously with the movement to the left, the pilot piston PP also moves against the spring 21. As the pilot piston PP moves, the push rod 22 pushes the pilot poppet PV open.

When the pilot poppet PV is opened, the back pressure chamber 13 communicates with the spool side 3 a of the actuator port 3 through the discharge passage 24. At this time, since the spool side 3a of the actuator port 3 communicates with the return passage 5 via the first annular groove 11, the back pressure chamber 13 is discharged to the return passage 5 via the discharge passage 24. The Therefore, the back pressure of the main poppet MP decreases and the main poppet MP opens, but the principle is exactly the same as that of the conventional device. At this time, the through-hole 16 is kept closed.

Further, when the main spool MS moves in the left direction of the drawing as described above, the supply passage 2 and the actuator port 4 communicate with each other through the second annular groove 12, so that the fluid in the head side chamber of the cylinder C is Actuator side 3 b of actuator port 3 → spool side 3 a → first annular groove 11 → returned to the tank via return passage 5.

  However, in the above case, the main poppet MP is opened before the notch 23 formed at the edge of the first annular groove 11 communicates with the return passage 5 for the following reason. For example, when the main poppet MP is opened after the notch 23 is opened, the return flow rate from the cylinder C flows into the notch 23 at the instant when the main poppet MP is opened. However, the notch 23 is used for inching control while slightly changing the communication opening degree between the actuator port 3 and the return passage 5. If the return flow rate flows into the notch 23 having such a function at once, it is difficult to perform the delicate inching control. Therefore, as described above, the main poppet MP is opened first, and after returning to the spool side 3a of the actuator port 3 to reach the flow rate, the notch 23 is opened so that accurate inching control can be performed. Yes.

It is sectional drawing of this invention. It is sectional drawing of the conventional cylinder fall prevention valve apparatus.

B Valve body 2 Supply passage 3, 4 Actuator port 5, 6 Return passage C Cylinder MS Main spool 7, 8 Main pilot chamber 11 First annular groove 12 Second annular groove
16 Through-hole MP (which is an on-off valve part) Main poppet PP Pilot piston 23 Notch 24 Discharge passage

Claims (1)

A main spool incorporating slidably in the valve body, a pair of main pilot chamber to face the ends of the main spool, an actuator port formed in the valve body, a cylinder connected to the actuator port, the valve formed in the body, and a supply passage communicating with said actuator ports through the annular groove in which the main spool is formed in the main spool when moved in one direction, when said main spool is moved in the other direction directing a return passage communicating with said actuator ports through the annular groove, a main poppet provided in the passage process of connecting the annular groove and the actuator port, a load pressure of the actuator causes faces the main poppet Back pressure chamber and for opening and closing this back pressure chamber And b lot poppet, and the pilot piston to push open the pilot poppet, in the cylinder drop valve device provided with a pilot chamber for guiding the pilot pressure to act on the pilot piston, when the pilot poppet is opened, the back pressure a chamber for the return flow of the actuator ports, provided with a discharge passage for communicating with the actuator port on the downstream side with respect to the main poppet, when the pilot poppet is closed, the back pressure chamber and the actuator and a port communicated with, when the pilot poppet is opened, Rutotomoni the main provided an opening and closing valve portion to block the communication between the actuator port to be upstream of the back pressure chamber and the main poppet to said pilot poppet On the spool The annular groove, the cylinder drop prevention valve device forming a notch communicating with said return passage.

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