JP6217868B2 - Control valve - Google Patents

Description

  The present invention relates to a control valve used in a hydraulic circuit of an industrial vehicle or the like.

  Examples of control valves that are widely used as those mounted on industrial vehicles such as forklifts include the following.

  This control valve constitutes a hydraulic circuit that supplies hydraulic fluid pressure to the cylinder cap 2a side of the hydraulic actuator 2 that drives the lift L that is the drive target. As shown in FIGS. 4 and 5, the control valve includes a housing 1, a spool valve body 3 capable of moving forward and backward within a sleeve 1 e provided in the housing 1, and a lift lock poppet valve 4 built in the housing 1. It has.

  The housing 1 communicates with a high-pressure passage 1 a that communicates with a pump P that is a hydraulic fluid supply source, a low-pressure passage 1 b that communicates with a tank T for storing hydraulic fluid, and a cylinder cap 2 a of a hydraulic actuator 2. And a sleeve 1e that is connected to the high-pressure passage 1a, the low-pressure passage 1b, and the cylinder passage 1c, and in which the spool valve body 3 is slidable. A hydraulic fluid discharge passage 1d communicating with the low-pressure passage 1b is branched from the cylinder passage 1c when the spool valve body 3 takes a lowered position D described later.

  The spool valve body 3 communicates between the high pressure passage 1a and the neutral position C that blocks the low pressure passage 1b and the cylinder passage 1c, and between the low pressure passage 1b and the cylinder passage 1c. And a switching valve that selectively takes the rising position U as shown in FIG. 5, which communicates between the lowering position D and the high-pressure passage 1a and the cylinder passage 1c.

  The lift lock poppet valve 4 can be in an open state in which the hydraulic actuator 2 and the sleeve 1e are communicated with each other and in a closed state in which the hydraulic actuator 2 and the sleeve 1e are blocked. Further, the lift lock poppet valve 4 is energized in a direction in which the poppet valve body 4a having a back pressure chamber 4a1 therein and the poppet valve body 4a are seated on the valve seat (the lift lock poppet valve 4 is closed). The spring 4b is used. The on-off valve of the lift lock poppet valve 4 is operated by the pressure difference between the inside and outside of the back pressure chamber 4a1.

  The housing 1 further includes a back pressure passage 1g in which a solenoid valve 5 is provided in the middle of communication between the back pressure chamber 4a1 and the hydraulic fluid discharge passage 1d.

  The control valve uses an emergency operation valve 62 that is provided so as to be able to advance and retreat between a use position R that presses the poppet valve body 4a and a retracted position S that is separated from the poppet valve body 4a. 6 is further provided. The emergency operation valve 6 includes an emergency valve plug 61 attached to the housing 1 and the emergency operation valve body 62 partially disposed in the emergency valve plug 61. More specifically, the emergency valve plug 61 is provided with a female screw 611, and the emergency operation valve body 62 is provided with a male screw 621 that can be screwed into the female screw 611. In addition, the emergency operation valve element 62 is screwed back and forth with respect to the emergency valve plug 61 and the housing 1 by manual operation.

  If the spool valve body 3 of the control valve is moved to the lowered position D by operating a lever or the like while the operator is seated on the driver's seat, the solenoid valve 5 is normally opened to cause the back pressure of the poppet valve body 4a. The hydraulic fluid is discharged from the chamber 4a1 to the tank T through the cylinder passage 1c, the hydraulic fluid discharge passage 1d, and the low pressure passage 1b, and a differential pressure is generated between the inside and the outside of the back pressure chamber 4a. At this time, the lift lock poppet valve 4 is opened by a force derived from the differential pressure, and the hydraulic fluid guided from the hydraulic actuator 2 to the cylinder passage 1c is directly guided to the hydraulic fluid discharge passage 1d. It is discharged to the tank T through the low pressure passage 1b.

  On the other hand, when the solenoid valve 5 remains closed due to malfunction of the solenoid valve 5, the emergency operation valve element 6 is moved from the retracted position S to the use position R by manual operation as shown in FIG. The lift lock poppet valve 4 is opened by pressing the poppet valve body 4a (see, for example, Patent Document 1).

  By the way, in the vicinity of the cylinder passage 1c where the emergency operation valve 6 is provided, both the high-pressure hydraulic fluid from the pump P and the relatively low-pressure hydraulic fluid returned from the hydraulic actuator 2 to the tank T circulate. To do. Therefore, when the spool valve body 3 reaches the raised position U as shown in FIG. 5, part of the high-pressure hydraulic fluid supplied from the pump P is between the emergency operation valve body 62 and the emergency valve plug 61. The gap 6s is reached.

  In the conventional configuration, as shown in FIGS. 4 to 6, an O-ring 623 is disposed between the emergency operation valve body 62 and the emergency valve plug 61 to prevent liquid leakage from the gap 6s. . However, when the spool valve body 3 reaches the raised position U, the high-pressure hydraulic fluid may reach the gap 6s, and the O-ring 623 may protrude from the gap and be damaged. When the O-ring 623 is damaged, a problem that liquid leakage is likely to occur occurs.

  In order to suppress the occurrence of such a problem, it is conceivable to reduce the gap between the emergency operation valve element and the emergency valve plug or to provide a backup ring separately. However, when the former is adopted, it is necessary to form a certain gap between the emergency operation valve element and the emergency valve plug so that the emergency operation valve element can slide while preventing the O-ring from protruding, and high machining accuracy. Another problem arises that is required. In addition, when the latter is adopted, there arises a new problem such as an increase in the number of parts due to separately providing a backup ring in addition to an O-ring and an increase in manufacturing effort associated therewith.

  The problems as described above can also be caused by a configuration in which a hydraulic fluid discharge passage that directly connects the back pressure chamber and the spool is provided. When such a configuration is adopted, when the spool valve body is in the neutral position for a long time, the hydraulic fluid pressure in the portion closer to the actuator than the poppet valve body in the cylinder passage and the hydraulic fluid pressure in the hydraulic fluid discharge passage are equal for a long time. This is because the hydraulic fluid pressure becomes relatively high particularly when the load loaded on the lift is large.

JP 2013-57363 A

  An object of the present invention is to suppress liquid leakage without requiring high processing accuracy and without using special parts.

  In order to solve the above problems, the control valve according to the present invention has a configuration as described below. That is, the control valve according to the present invention includes a high-pressure passage that communicates with a hydraulic fluid supply source, a low-pressure passage that communicates with a tank for storing hydraulic fluid, a cylinder passage that communicates with a hydraulic actuator, and these high-pressure passages, A housing having a sleeve connected to the passage and the cylinder passage; an open position provided in the cylinder passage for communicating the sleeve and the hydraulic actuator; and a blocking position for shutting off the sleeve and the hydraulic actuator. A lift lock poppet valve having a poppet valve body having a back pressure chamber inside, and a back pressure in which a solenoid valve is provided in the middle of communicating the back pressure chamber of the poppet valve body and the low pressure passage. Advancing and retreating between the passage and the use position for pressing the poppet valve body and the retreat position for separating from the poppet valve body And an emergency operation valve with very operation valve body to perform mechanical seal seated on the valve seat when provided in capacity take the retracted position.

  In such a case, when the emergency operation valve body is arranged at the retracted position, the emergency operation valve body is seated on the valve seat and performs mechanical sealing, so that the high-pressure hydraulic fluid is positioned near the emergency operation valve body. Even when the emergency operation valve body is led to, the entry into the gap between the emergency operation valve body and the emergency valve plug that advances and retracts the emergency operation valve body inside is suppressed. Therefore, it is possible to suppress the occurrence of problems caused by the high-pressure hydraulic fluid entering the gap between the emergency operation valve element and the emergency valve plug. In particular, when an O-ring is provided in the gap, when the emergency operation valve element moves back and forth between the retracted position and the use position, the leakage of the hydraulic fluid guided to the gap is prevented. It can be effectively suppressed by the ring.

  According to the present invention, liquid leakage can be suppressed without requiring high machining accuracy and without using special parts.

Schematic which shows the control valve which concerns on one Embodiment of this invention. Operation | movement explanatory drawing of the control valve which concerns on the same embodiment. Schematic which shows the emergency operation valve which concerns on the same embodiment. Schematic which shows the conventional control valve. The operation explanatory view of the conventional control valve. Schematic which shows the conventional emergency operation valve.

  An embodiment of the present invention will be described below with reference to FIGS. In the following description, parts corresponding to those in the conventional control valve described with reference to FIGS. 4 to 6 are denoted by the same names and symbols.

  As shown in FIGS. 1 and 2, the control valve according to this embodiment is mounted on a forklift and constitutes a hydraulic circuit for supplying hydraulic pressure to a hydraulic actuator 2 that drives a lift L that is a drive target. To do. Specifically, the control valve includes a housing 1, a spool valve body 3 slidable in a sleeve 1 e provided in the housing 1, and a lift lock poppet valve provided in a cylinder passage 1 c inside the housing 1. 4 and an emergency operation valve body provided between the use position R for pressing the poppet valve body 4a of the lift lock poppet valve 4 and the retracted position S separated from the poppet valve body 4a of the lift lock poppet valve 4 The emergency operation valve 6 having 62 is provided.

  The housing 1 has the same configuration as that well known for use in this type of control valve. More specifically, the high-pressure passage 1a that communicates with the pump P that is the hydraulic fluid supply source, the low-pressure passage 1b that communicates with the tank T for storing the hydraulic fluid, and the lift L that is the drive target are driven. A cylinder passage 1c communicating with the cylinder cap 2a of the hydraulic actuator 2 and a sleeve 1e connected to the high pressure passage 1a, the low pressure passage 1b and the cylinder passage 1c are provided. A hydraulic fluid discharge passage 1d communicating with the low-pressure passage 1b is branched from the cylinder passage 1c when the spool valve body 3 takes a lowered position D described later.

  The spool valve body 3 has the same configuration as that known for use in this type of control valve. That is, the spool valve body 3 has a neutral position C that blocks between the high pressure passage 1a and the low pressure passage 1b and the cylinder passage 1c, and the hydraulic fluid between the low pressure passage 1b and the cylinder passage 1c. A lowered position D as shown in FIG. 1, which is communicated via the discharge passage 1d, and a raised position U as shown in FIG. 2, which is communicated between the high pressure passage 1a and the cylinder passage 1c, are selectively used. The switching valve can be configured.

  The lift lock poppet valve 4 has the same configuration as that known for use in this type of control valve. That is, the lift lock poppet valve 4 takes an open state in which the sleeve 1e and the cylinder cap 2a are in communication and a cut-off state in which the sleeve 1e and the cylinder cap 2a are blocked. The lift lock poppet valve 4 uses a poppet valve body 4a and a spring 4b that urges the poppet valve body 4a in a direction to seat the poppet valve body 4a (close the lift lock poppet valve 4). The poppet valve body 4a has a back pressure chamber 4a1. The housing 1 is provided with a back pressure passage 1g provided with a solenoid valve 5 in the middle of communicating the back pressure chamber 4a1 and the cylinder passage 1b. The back pressure chamber 4a1 communicates with the cylinder passage 1c through the back pressure passage 1g. The back pressure chamber 4a1 communicates with the tank T through the hydraulic fluid discharge passage 1d and the low pressure passage 1b when the spool valve body 3 assumes the lowered position D.

  The solenoid valve 5 has the same configuration as that known for use in this type of control valve. That is, the solenoid valve 5 opens when the spool valve body 3 is in the lowered position D and satisfies the solenoid valve opening condition that the operator is not away.

  The emergency operation valve 6 is for manually opening the lift lock poppet valve 4 when the solenoid valve 5 does not open even though the solenoid valve opening condition is satisfied. Specifically, as shown in FIGS. 1 to 3, an emergency valve plug 61 disposed at a position facing the cylinder passage 1 c of the housing 1, and an emergency operation valve body 62 capable of moving back and forth in the emergency valve plug 61. And.

  As shown in FIG. 3, the emergency valve plug 61 has a female thread portion 611 and a valve element insertion hole 612 located in a portion closer to the lift lock poppet valve 4 than the female thread portion 611.

  As shown in FIG. 3, the emergency operation valve body 62 is provided on the side of the lift lock poppet valve 4 with respect to the male screw portion 621 that can be screwed with the female screw portion 611 of the emergency valve plug 61 and the male screw portion 621. A body 622 that slides in the valve body insertion hole 612, an O-ring 623 disposed between the body 622 and the valve body insertion hole 612, and projects from the body 622 toward the lift lock poppet valve 4 to be used. A pressing portion 624 that presses the poppet valve body 4a when taking R, and a seat 613 of the emergency valve plug 61 that is provided between the pressing portion 624 and the body 622 and takes the retracted position S. And a seal portion 625 for performing a mechanical seal.

  Here, when the spool valve body 3 is moved from the neutral position C to the lowered position D by a lever operation or the like while the operator is seated on the driver's seat, the solenoid valve 5 is normally opened, and the poppet valve body 4a The hydraulic fluid in the back pressure chamber 4a1 is guided to the tank T through the hydraulic fluid discharge passage 1d and the low pressure passage 1b, thereby generating a differential pressure between the inside of the back pressure chamber 4a1 and the outside thereof. The poppet valve body 4a is separated from the valve seat by the force derived from the above, and the hydraulic fluid from the hydraulic actuator 2 is guided to the tank T.

  On the other hand, when the solenoid valve 5 is not opened due to a failure or the like when the spool valve body 3 is moved from the neutral position C to the lowered position D, as shown in FIG. When the screw is fed by manual operation, the poppet valve element 4a approaches the poppet valve element 4a, further moves to the use position R, and presses the poppet valve element 4a to open the lift lock poppet valve 4. After the operation of lowering the lift L is completed, when the spool valve body 3 is returned from the lowered position D to the neutral position C, the emergency operation valve body 62 receives a manual operation and is screwed to the retracted position. Then, the seal portion 625 is seated on the valve seat 613 while moving away from the poppet valve body 4a. Here, when the emergency operation valve body 62 moves back and forth between the retracted position S and the use position R, the clearance 6s between the emergency operation valve body 62 and the emergency valve plug 61 is caused by the O-ring 623. The leakage of the hydraulic fluid led to is suppressed.

  Further, when the spool valve body 3 is moved from the neutral position C to the raised position U by a lever operation or the like while the operator is seated in the driver's seat, as shown in FIG. It is guided to the hydraulic actuator 2 through the cylinder passage 1c. At this time, the pressing portion 624 of the emergency operation valve body 62 receives a hydraulic pressure from the hydraulic fluid from the high pressure passage 1a. However, since the seal portion 625 of the emergency operation valve body 62 is seated on the valve seat 613 and performs mechanical sealing, the hydraulic fluid guided to the gap 6s between the emergency operation valve body 62 and the emergency valve plug 61 is provided. Is a small amount and its hydraulic pressure is smaller than the hydraulic pressure from the pump P.

  That is, according to the present embodiment, when the emergency operation valve body 62 is at the retracted position S, the seal portion 625 is seated on the valve seat 613 and performs mechanical sealing, so that the following effects are obtained. can get. Specifically, since the hydraulic pressure of the hydraulic fluid guided to the gap 6s between the emergency operation valve body 62 and the emergency valve plug 61 is smaller than the hydraulic pressure from the pump P, the high-pressure hydraulic fluid is operated in an emergency operation. By entering between the valve body 62 and the housing 1, the O-ring 623 protrudes from the gap and is damaged, and it is possible to suppress the occurrence of problems that cause liquid leakage. In addition, since the hydraulic pressure of the hydraulic fluid guided to the gap 6s becomes small, the hydraulic fluid guided to the gap 6s when the emergency operation valve body 62 moves back and forth between the retracted position S and the use position R, etc. Can be effectively suppressed by the O-ring 623.

  In addition, this embodiment is not restricted to embodiment mentioned above.

  For example, in the embodiment described above, the back pressure passage is branched from the cylinder passage, and the hydraulic fluid discharge passage is branched from the cylinder passage. However, the control valve has the following configuration. The present invention may be applied to. That is, in a control valve having a mode in which a hydraulic fluid discharge passage directly connecting the back pressure chamber and the spool is provided and a solenoid valve and an emergency operation valve are provided in the middle of the hydraulic fluid discharge passage, the present invention is applied to the valve body of the emergency operation valve. You may apply.

  In addition, in the above-described embodiment, the emergency valve plug is attached to the housing, and the emergency operation valve body is configured to be able to advance and retreat inside the emergency valve plug, but the hole for inserting the emergency operation valve body into the housing The present invention may be applied to a control valve that is directly drilled.

  In addition, various changes may be made without departing from the spirit of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the control valve of the structure which can suppress a liquid leak can be provided, without request | requiring a high processing precision and without using a special component.

DESCRIPTION OF SYMBOLS 1 ... Housing 3 ... Spool valve body 4 ... Lift lock poppet valve 4a ... Poppet valve body 4a1 ... Back pressure chamber 6 ... Emergency operation valve 61 ... Plug 613 ... Valve seat 62 ... Emergency operation valve body 625 ... Seal part P ... Hydraulic fluid Pressure supply source (pump)
T ... Tank

Claims (1)

High pressure passage communicating with hydraulic fluid supply source, low pressure passage communicating with tank for storing hydraulic fluid, cylinder passage communicating with hydraulic actuator, and sleeve connected to these high pressure passage, low pressure passage and cylinder passage A housing having
A poppet provided in the cylinder passage and capable of taking an open position for communicating the sleeve and the hydraulic actuator, and a blocking position for blocking the sleeve and the hydraulic actuator, and having a back pressure chamber inside. A lift lock poppet valve having a valve body;
A back pressure passage provided with a solenoid valve in the middle of communicating the back pressure chamber of the poppet valve body and the low pressure passage;
It has an emergency operation valve body that is provided so as to be able to advance and retreat between a use position for pressing the poppet valve body and a retreat position that is separated from the poppet valve body and that sits on the valve seat and mechanically seals when taking the retreat position A control valve equipped with an emergency operation valve.

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