JP3923993B2 - Air venting device in upper pilot oil chamber in vertical spool type switching valve. - Google Patents

Description

The present invention relates to a hydraulic pilot type switching valve mounted on a construction machine such as a hydraulic excavator, and more particularly, in an upper pilot oil chamber in a vertical spool type switching valve arranged so that the spool operation of the switching valve is in a vertical direction. Relates to the device.

  In general, in a construction machine such as a hydraulic excavator, a hydraulic pilot type switching valve is used to control various actuators. As this type of hydraulic pilot type switching valve, one having the configuration shown in FIG. 3 is known.

  That is, in FIG. 3, this type of switching valve 10 includes a valve body 11 provided on a vehicle body frame 13, and hydraulic oil supplied from the main pump 30 to an actuator (cylinder) 40 is supplied to the valve body 11. The upper part is provided with an inlet port 12, a center bypass passage 14, a return passage 16, and an outlet port 18 that flow in the lateral direction, and from which the pilot pressure oil from the remote control valve 50 to the switching spool 20 acts from above or below. A pilot port 22 and a lower pilot port 24 are provided. A switching spool 20 is arranged between the pilot ports 22 and 24 so as to make a vertical stroke in the vertical direction.

  Thus, the reason why the switching spool 20 is arranged so as to operate vertically in the vertical direction is that a lot of other devices are installed around the switching valve and there is little space, and there is space above it. This is because the operation is simplified when the switching spool 20 is maintained and replaced. Therefore, according to this type of switching valve (referred to as a vertical spool type switching valve), the switching spool 20 can be easily pulled out simply by removing the cover 22a of the upper pilot port 22. That is, the switching spool 20 can be easily removed from the valve body 11 of the switching valve 10 with members such as the cap 20a, the guide 20b, the stopper 20c, and the spring 20d for controlling the position of the switching spool 20 being attached. It is possible to pull it out.

  In FIG. 3, the switching valve 10 is composed of a composite control valve having three switching spools. However, the connection configuration of the actuator and remote control valve corresponding to the other two switching spools is described above. The illustration is omitted for the sake of simplicity.

  However, the operation of the vertical spool type switching valve 10 will be briefly described. First, when the remote control valve 50 is in the neutral state as shown in FIG. 3, the switching valve 10 is also in the neutral state as shown in the figure, so that the hydraulic oil from the main pump 30 flows from the pump line 32 to the inlet port 12. Then, the refrigerant is returned to the tank 36 through the center bypass passage 14, the return passage 16, the outlet port 18 and the tank line 34, through the cooler 34 a and the filter 34 b.

  Next, when the operation lever 50a of the remote control valve 50 is operated, for example, to the left by a predetermined amount, pilot pressure oil having a pressure proportional to the operation angle of the operation lever 50a is supplied from one pilot line 54a to the upper pilot port 22. The switching spool 20 is moved downward in the drawing to a position where the force generated in the pilot oil chamber 22a is balanced with the elastic force of the spring 20d.

  At this time, the supply passage 26a connected to the inlet port 12 of the switching valve 10 and the cylinder port 42a communicate with each other, the cylinder port 42b and the return passage 16 communicate with each other, and the center bypass passage 14 and the return passage 16 are connected to each other. Since the center groove 43 provided on the switching spool 20 is throttled, the flow rate flowing from the center bypass passage 14 to the return passage 16 is reduced, and the reduced amount of hydraulic fluid is supplied from the supply passage 26a to the cylinder port 42a and It is supplied to the actuator 40 via the actuator line 44a. The return oil from the actuator 40 is returned to the tank 36 from the actuator line 44b through the cylinder port 42b, the return passage 16, the outlet port 18 and the tank line 34, and further through the cooler 34a and the filter 34b.

  Therefore, according to the vertical spool type switching valve configured as described above, the opening speed of the center groove 43 on the switching spool 20 which is controlled by the position of the switching spool 20 in many cases is controlled in the speed control of the actuator in the construction machine. It can be performed by adjusting the area, that is, by controlling the flow rate of the hydraulic oil that bleeds off from the center bypass passage 14 to the return passage 16 (bleed-off flow rate control).

  Since the operation when the operation lever 50a is operated to the right side is the same as described above, the description thereof is omitted.

  As described above, this type of vertical spool type switching valve is intended to improve the workability of maintenance and replacement of the spool by configuring the spool to operate in the vertical direction. There is an essential difficulty that the responsiveness of the switching valve is lowered. That is, the gas mixed in the pilot pressure oil is gradually accumulated in the pilot oil chamber 22b in the cover 22a of the upper pilot port 22 via the pilot line 54a, and this accumulated air is more compressible than oil. Since the (volume reduction ratio with respect to pressure) is large, it takes a considerable time for the pressure in the pilot oil chamber 22b to reach a specified pressure after the operation lever 50a of the remote control valve 50 is operated. The response of the switching valve 10 to the operation is deteriorated.

  For this reason, in the conventional vertical spool type switching valve of this type, the gas is manually discharged or a special automatic air venting device or the like is provided (for example, Japanese Utility Model Publication No. 3-49286). Publication). However, in the above configuration, it is obvious that the former case is extremely complicated. Further, in the latter case, an additional drain pipe is required in the pilot oil chamber, so that not only the manufacturing cost increases, but in the case of a composite control system having a plurality of spools, the drain pipe is formed by one. In order to complete the maintenance, the cover to be provided for each spool has an integrated structure, and it is necessary to attach and detach the pilot pressure oil piping of the spool that does not require the replacement of the spool when performing maintenance and replacement of the spool. The maintenance time and replacement work time of the spool increase, and the maintenance cost also increases.

  Further, in an emergency, since it is necessary to operate the spool even when the engine of the construction machine is stopped, an accumulator 58 that accumulates the pressure oil of the pilot pump 52 is provided. In this case, if the flow rate of the pilot pressure oil leaking from the drain passage is large, the pressure oil immediately accumulated in the accumulator 58 is reduced, and the spool cannot be operated. Therefore, an expensive accumulator having a large capacity is required. There are difficulties.

  Note that the air staying in the pilot oil chamber 24b in the cover 24a of the lower pilot port 24 of the switching valve 10 collects in the pilot oil chamber 24b, so that the switching spool 20 and the valve body 11 of the switching valve 10 Since it is easy to escape to the return passage 16 from the gap between them, and it is not necessary to provide a position control member (cap 20a, guide 20b, stopper 20c, spring 20d, etc.) of the spool 20 in the pilot oil chamber 24b. The volume of the pilot oil chamber 24b is smaller than the volume of the pilot oil chamber 22b of the upper pilot port 22, and even if air stays there, there is no effect that the response of the switching valve 10 becomes a problem. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic pilot type switching valve provided so as to operate the spool in the vertical direction. The vertical spool can easily and reliably achieve air venting without requiring additional piping. An object of the present invention is to provide an air venting device in an upper pilot oil chamber in a mold switching valve.

In order to achieve the above object, an air vent device in an upper pilot oil chamber in a vertical spool type switching valve according to the present invention includes an inlet port into which hydraulic oil for driving an actuator flows, an outlet port connected to a tank, A return passage through which the return oil from the actuator flows in and connected to the outlet port, and pilot pressure oil for the switching spool provided from the pilot line, act from above and below via the upper and lower pilot oil chambers, respectively. An upper pilot port and a lower pilot port to be ventilated, and the upper pilot oil chamber is bleed in a vertical spool type switching valve arranged between the pilot ports so as to vertically move the switching spool vertically. A device connecting the outlet port and the tank A cooler and a filter as back pressure generating means provided in the tank line, and a valve body of the vertical spool type switching valve, and the upper pilot oil chamber and the return passage in the vicinity of a stroke end of the switching spool. And a pilot oil passage formed to be able to communicate with each other, and the pilot oil passage is directed to the upper pilot oil chamber under the action of pilot pressure oil applied to the lower pilot oil chamber. The upper pilot oil chamber and the return passage communicate with each other when moved to the vicinity of the stroke end, and back pressure generated by the cooler and the filter acts on the upper pilot oil chamber via the return passage. Thereby, the oil in the upper pilot oil chamber together with the air staying in the oil chamber Via connection pilot line, characterized by being configured to flow into the tank.

  In that case, the pilot oil passage includes a spool hole of the switching spool located between the upper pilot oil chamber and the return passage, and a groove formed on a circumference of a spool land inserted through the spool hole. Thus, an orifice can be formed.

An air vent device in an upper pilot oil chamber in a vertical spool type switching valve according to the present invention includes an inlet port into which hydraulic oil for driving an actuator flows, an outlet port connected to a tank, and an outlet port connected to the outlet port. An upper pilot port and a lower pilot that act as a return passage through which return oil from the actuator flows and pilot pressure oil for a switching spool provided from a pilot line from above and below through the upper and lower pilot oil chambers, respectively. And a device for venting the upper pilot oil chamber in a vertical spool type switching valve, wherein the switching spool is disposed so as to move vertically between the pilot ports. Provided in the tank line connecting the port and tank A cooler and a filter as back pressure generating means and a valve body of the vertical spool type switching valve are provided so that the upper pilot oil chamber and the return passage can be connected to each other in the vicinity of the stroke end of the switching spool. A pilot oil passage formed, and the pilot oil passage is operated under the action of pilot pressure oil applied to the lower pilot oil chamber, and the switching spool is directed toward the upper pilot oil chamber to the vicinity of the stroke end. When moved, the upper pilot oil chamber and the return passage are opened to communicate with each other, and back pressure generated by the cooler and the filter is applied to the upper pilot oil chamber via the return passage. Pilot connected to the upper pilot oil chamber together with the air staying in the oil chamber Since it is configured to flow to the tank via the in-line, air venting in the valve body can be achieved easily and reliably with a simple configuration that only pierces the pilot oil passage, and is additionally provided as in the past. The air staying on the pilot oil chamber side can smoothly flow out together with the oil flowing in the pilot oil passage from the return passage toward the pilot oil chamber without providing piping equipment.

Next, an embodiment of the air venting device in the upper pilot oil chamber in the vertical spool type switching valve according to the present invention will be described in detail with reference to the accompanying drawings. For convenience of explanation, the same components as those of the conventional configuration shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted.

First, the configuration of the air venting device in the upper pilot oil chamber in the vertical spool type switching valve in the present embodiment is basically the same as the conventional configuration shown in FIG. Accordingly, a brief description will be given again, but in FIG. 1, the hydraulic pilot type switching valve 10 of this embodiment basically comprises a valve body 11 provided on the vehicle body frame 13. On the other hand, it is provided with an inlet port 12, a center bypass passage 14, a return passage 16, and an outlet port 18 through which hydraulic fluid supplied from the main pump 30 to the actuator 40 flows in the lateral direction, and is switched from the remote control valve 50. An upper pilot port 22 and a lower pilot port 24 are provided for applying pilot pressure oil to the spool 20 from above or below. The switching spool 20 is arranged between the pilot ports 22 and 24 so as to move vertically in the vertical direction.

  Therefore, when the operation lever 50a of the remote control valve 50 is operated, for example, to the left side, the pilot pressure oil having a pressure proportional to the operation angle of the operation lever 50a is supplied from one pilot line 54a to the pilot oil chamber 22a of the upper pilot port 22. The switching spool 20 is moved downward in the drawing to a position where the force generated by this is balanced with the elastic force of the spring 20d.

  At this time, the supply passage 26a connected to the inlet port 12 of the switching valve 10 and the cylinder port 42a communicate with each other, the cylinder port 42b and the return passage 16 communicate with each other, and the center bypass passage 14 and the return passage 16 are connected to each other. Since the center groove 43 provided on the switching spool 20 is throttled, the flow rate flowing from the center bypass passage 14 to the return passage 16 is reduced, and the reduced amount of hydraulic fluid is supplied from the supply passage 26a to the cylinder port 42a and It is supplied to the actuator 40 via the actuator line 44a. The return oil from the actuator 40 is returned to the tank 36 from the actuator line 44b through the cylinder port 42b, the return passage 16, the outlet port 18 and the tank line 34, and further through the cooler 34a and the filter 34b.

  However, in this embodiment, as shown in an enlarged view in FIG. 2, in the above-described configuration, the valve body is located between the pilot oil chamber 22 b of the upper pilot port 22 and the return passage 16 connected to the outlet port 18. A groove 62a is provided on the circumference of the spool land 60 of the switching spool 20 that is inserted into the spool hole 62b that is formed in the hole 11. This groove 62a is operated in the vicinity of the stroke end when the operation lever 50a of the remote control valve 50 is operated rightward to pressurize the pilot oil chamber 24b of the lower pilot port 24 and the switching spool 20 moves upward. A pilot oil passage 62 that connects the pilot oil chamber 22 b of the upper pilot port 22 and the return passage 16 is formed. Therefore, the groove 62a forming the pilot oil passage 62 is formed as an orifice having a small opening area between the groove 62a and the spool hole 62b provided in the valve body 11.

  Therefore, in this case, in a general construction machine, the flow rate of the discharge oil of the main pump 30 returning from the outlet port 18 of the switching valve 10 to the tank 36 or the return oil from the actuator 40 is a relatively large flow rate. Due to the flow path resistance of the line 34, the cooler 34a, the filter 34b, etc., a back pressure of about 0.5 MPa is usually generated in the outlet port 18 and the return passage 16 connected thereto. On the other hand, unless the pressure of the upper pilot port 22 and the lower pilot port 24 is increased by the remote control valve 50, no oil flows from the pilot ports 22 and 24 to the remote control valve 50. That is, it is equal to the atmospheric pressure.

  Next, the air venting operation and its operation in the switching valve of the present embodiment having such a configuration will be described.

  When air 64 stays (accumulates) in the cover 22a and / or the pilot oil chamber 22b of the upper pilot port 22, first, the operation lever 50a of the remote control valve 50 is tilted to the right from the state shown in FIG. As a result, the pilot pressure oil from the pilot pump 52 acts in the pilot oil chamber 24b of the lower pilot port 24 from the pilot line 54b in the lower part of the figure, and moves the switching spool 20 in the upper part of the figure.

  As shown in FIG. 2, when the switching spool 20 is raised to the vicinity of its stroke end, the pilot oil passage 62 opens as described above, and returns to the pilot oil chamber 22b through the groove 62a and the spool hole 62b. The passage 16 communicates. At this time, the pressure in the return passage 16 is about 0.5 MPa, and the pressure in the pilot oil chamber 22b is atmospheric pressure, so a part of the discharge oil from the main pump 30 or the return oil from the actuator 40 (ΔQ) passes from the return passage 16 through the spool hole 62b and the groove 62a (pilot oil passage 62), the pilot oil chamber 22b, the gap between the cover 22a and the guide 20b, the upper pilot port 22, and the pilot line 54a. Is returned to the tank 36 through a tank line 56 in the remote control valve 50 shown in FIG. Accordingly, the air 64 staying in the cover 22a and / or the pilot oil chamber 22b of the upper pilot port 22 can flow out to the tank 36 along with the oil.

  The opening area of the orifice formed by the groove 62a forming the pilot oil passage 62 and the spool hole 62b can be set small so that a small amount of oil that can flow out of air can flow. The back pressure generated in the pilot oil chamber 22b due to the flow path resistance of the pilot line 54a, the remote control valve 50, and the like is so low that it can be ignored. Moreover, since the switching valve 10 performs bleed-off flow rate control in many cases as described above, the center groove 43 of the switching spool 20 blocks the center bypass passage 14 and the return passage 16 before The flow rate control performance does not depend on the position of the spool 20 until the stroke end of the spool 20. Accordingly, if the timing at which the groove 62a of the pilot oil passage 62 opens to the pilot oil chamber 22b is set near the stroke end of the switching spool 20, even if some back pressure is generated in the pilot oil chamber 22b, In practical use, the flow rate control performance does not deteriorate.

  On the contrary, when the operation lever 50a of the remote control valve 50 is tilted to the left, the pilot pressure oil from the pilot pump 52 acts in the pilot oil chamber 22b of the upper pilot port 22 from the pilot line 54a. Then, the switching spool 20 is moved downward (see FIG. 1). In this case, since the space between the pilot oil chamber 22b and the return passage 16 is blocked by the spool land 60 of the spool 20, the discharge oil of the pilot pump 52 or the accumulated oil of the accumulator 58 returns from the pilot oil chamber 22b. The amount of oil leaking into the passage 16 is extremely small. Therefore, according to the present embodiment, it is not necessary to increase the capacity of the accumulator 58.

  In this manner, according to the present invention, the air venting in the valve body 11 can be easily and reliably achieved simply by forming the pilot oil passage 62 by drilling it in the valve body 11. In addition, in this case, since the configuration is simple, no additional equipment is required as in the prior art, and maintenance and replacement workability by pulling out the switching spool 20 is not impaired.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and many design changes can be made without departing from the spirit of the present invention.

FIG. 3 is a cross-sectional view of a main part showing an embodiment of an air venting device in an upper pilot oil chamber in the vertical spool type switching valve according to the present invention and its control system diagram. FIG. 2 is an enlarged cross-sectional view showing a state in the vicinity of an ascending stroke end of a switching spool of an upper pilot port shown in FIG. 1. It is a principal part cross section which shows the air venting apparatus in the upper pilot oil chamber in the conventional vertical spool type switching valve, and its control system figure.

Explanation of symbols

10 switching valve 11 valve body 12 inlet port 13 body frame 14 center bypass passage 16 return passage 18 outlet port 20 switching spool 20a cap 20b guide 20c stopper 20d spring 22 upper pilot port 22a cover 22b upper pilot oil chamber 24 lower pilot port 24a cover 24b Lower pilot oil chamber 30 Main pump 32 Pump line 34 Tank line 34a Cooler 34b Filter 36 Tank 40 Actuator 42a, 42b Cylinder port 43 Center groove 44a, 44b Actuator line 50 Remote control valve 50a Operation lever 52 Pilot pump 54a, 54b Pilot line 56 Tank line 58 Accumulator 60 Spool land 62 Pilot oil passage 62a Groove 62b Spool hole 6 Air

Claims (2)

An inlet port into which hydraulic oil for driving the actuator flows, an outlet port connected to the tank, a return passage connected to the outlet port and into which return oil flows from the actuator, and a switching spool provided from a pilot line An upper pilot port and a lower pilot port that allow pilot pressure oil to act on the upper and lower pilot oil chambers from above and below, respectively, and the switching spool is vertically moved between the pilot ports. A device for venting the upper pilot oil chamber in a vertical spool type switching valve arranged to move vertically,
A cooler and a filter as back pressure generating means provided in a tank line connecting the outlet port and the tank;
A pilot oil passage provided in a valve body of the vertical spool type switching valve, and formed so that the upper pilot oil chamber and the return passage can communicate with each other in the vicinity of a stroke end of the switching spool;
The pilot oil passage is connected to the upper pilot oil chamber and the return when the switching spool moves to the vicinity of the stroke end toward the upper pilot oil chamber under the action of pilot pressure oil applied to the lower pilot oil chamber. The passage opens to the passage, and the back pressure generated by the cooler and the filter is applied to the upper pilot oil chamber via the return passage, so that the oil in the upper pilot oil chamber stays in the oil chamber. An air venting device for an upper pilot oil chamber in a vertical spool type switching valve, characterized in that the air flows to the tank through a pilot line connected to the upper pilot oil chamber together with the air flowing therethrough. The pilot oil passage includes a spool hole of the switching spool located between the upper pilot oil chamber and the return passage, and a groove formed on a circumference of a spool land inserted through the spool hole. The air venting device in the upper pilot oil chamber in the vertical spool type switching valve according to claim 1, which comprises an orifice.

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