JP3388799B2 - Switching valve with arm regeneration function - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a directional control valve for supplying and discharging pressure oil to and from a hydraulic cylinder used for driving an arm of a construction machine. The present invention relates to a switching valve having a regenerating function for regenerating most of oil discharged from a cylinder. [0002] When excavating soil using a power shovel,
The arm is bent from an appropriately extended state so that the tip of the shovel approaches the surface of the ground, and is further bent so that the shovel is pulled into the soil. The excavator is provided with a cylinder so that the arm bending operation is performed by extending the arm driving cylinder. In such a case, the first stage until the tip of the shovel approaches the surface of the shovel is driven at a relatively high speed, and the second stage thereafter is strongly driven at a slightly lower speed. For this reason,
The regeneration circuit used in the first stage is provided in the hydraulic circuit of the arm driving cylinder. The regeneration circuit is generally
Pressure oil from the pump is supplied to the head side pressure chamber of the arm driving cylinder, and most of the pressure oil in the rod side pressure chamber is supplied to the bottom side pressure chamber while a part is discharged to the tank via the throttle. It has become. In this regenerating state, the amount of oil that is regenerated and used for the pressure oil discharged from the rod-side pressure chamber is larger than the amount of oil supplied from the pump, so that the extension operation of the cylinder is performed faster. A conventional switching valve having a regeneration function has, for example, a configuration in which a main part is enlarged in FIG. When the spool 1 is driven in the direction of arrow 2 from the illustrated neutral position, pressure oil from the hydraulic pump pushes and opens the load check valve 4 from the main passage 3 to supply the passage 5, the annular groove 6 of the spool, The pressure is supplied to the head-side pressure chamber 10 of the arm driving cylinder 9 through the passage 7 and the pipe 8. Then, the oil in the rod-side pressure chamber 11 of the cylinder 9 is pushed out, enters the regeneration passage 15 from the opening 14 formed in the spool via the pipe 12 and the supply / discharge passage 13, and a part thereof passes through the throttle 16. Most of the remaining pressure is increased due to the presence of the throttle 16 and the check valve 18 in the spool is pushed open to be supplied to the supply passage 5 from the opening 19. Used for playback. In the conventional switching valve having the regeneration function described above, since the diameter of the spool is small in a small switching valve, a regeneration passage provided in the spool is inevitably provided. There is a problem that the cross-sectional area becomes small and the pressure loss becomes large. As the pressure loss increases, the regeneration rate deteriorates. SUMMARY OF THE INVENTION An object of the present invention is to provide a switching valve having a regeneration function configured to increase the cross-sectional area of a regeneration passage. SUMMARY OF THE INVENTION The present invention relates to a switching valve for connecting a first directional switching valve for supplying and discharging pressure oil to an arm cylinder and another second directional switching valve. A regeneration passage connected to a supply passage from a pump is provided in the main body of the first direction switching valve so as to be substantially along the supply / discharge passage of the first direction switching valve connected to the rod-side pressure chamber of the cylinder for use; The discharge passage connected at the time of the discharging operation is connected to the regeneration passage, a check valve is provided in the regeneration passage provided in the main body of the first directional control valve, and the discharge passage is connected to the second passage through a throttle. It is characterized by being connected to the discharge passage of the directional control valve. According to the above means, when the load is small in the extension operation of the arm cylinder, the pressure oil discharged from the rod side pressure chamber flows from the supply / discharge passage into the discharge passage.
Since the discharge passage is connected to the discharge passage of the second directional control valve via a throttle, a part of the pressure oil is discharged through the throttle, but most of the pressure oil pushes the check valve. It is opened, passes through the regeneration passage, flows into the supply passage, and is recycled.
If the load is large and the operating speed of the cylinder becomes slower than the speed limited by the throttle, regeneration is not performed. Since the regeneration passage is formed in the main body of the first directional control valve, the check valve is also formed in the main body of the first directional control valve.
Therefore, in the case of a small directional switching valve, the passage cross-sectional area can be surely formed larger than that provided in the spool. An embodiment of the present invention will be described with reference to FIGS. 1 is a first directional control valve, and FIG.
It is a directional control valve, and both directional control valves are connected in series like a directional control valve in a normal construction machine. The first direction switching valve 21 supplies and discharges pressure oil to and from the arm cylinder 9, and the second direction switching valve 22 supplies and discharges pressure oil to and from the other cylinder 9a. The cylinder 9 is connected to a supply / discharge passage 38 to be described later via the pipe 8 to the head side pressure chamber 10, and a supply / discharge passage 44 to be described later via the pipe 12 to the rod side pressure chamber 11. . The first directional control valve 21 has a spool 24 attached to a block-shaped main body 23.
The spool 24 is mounted on the pilot unit 2
The pilot pressure is supplied to the cylinders 5 and 26 to move leftward or rightward to switch the supply / discharge direction of the pressure oil to / from the cylinder 9. The main body 23 has a spool insertion hole 36 and enlarged portions 27, 28, 29, 30, 3 provided in the insertion hole.
1, 32, 33, 34, 35, a discharge passage 37 following the enlargement portion 27, a supply / discharge passage 38 following the enlargement portion 28, a supply passage (bridge passage) 39 following the enlargement portion 29, and a supply passage 39 following the enlargement portion 33. , A supply / discharge passage 44 following the enlarged portion 34 and a discharge passage 45 continuing to the enlarged portion 35. The main body 23 is disposed so that the regeneration passage 50 substantially extends along the enlarged portion 34 at the end of the supply / discharge passage 44 so as to connect the enlarged portions 33 and 35.
The check valve 51 is provided in the middle of the regeneration passage 50 with the direction from the enlarged portion 35 side to the enlarged portion 33 side being a forward direction.
Is provided. A discharge passage 53 connected to the discharge passage 45 via a throttle 52 is provided with the second directional control valve 22 in FIG.
Is connected to the discharge passage 53a. The spool 24 has annular grooves 55, 56, 5
7, 58. When the spool 24 moves to the left or right, the annular groove 55 connects the enlarged portion 28 to the enlarged portion 27 or 29, and the annular groove 58 connects the enlarged portion 34 to the enlarged portion 3.
3 or 35. In addition, the enlargement unit 3
Reference numerals 0 and 32 denote unload passages which are connected to the enlarged portion 31a of the second directional control valve 22. The enlarged portion 31 is connected to the tank and communicates with each other when the spool 24 is in the neutral position. , When the switching position is reached,
Between 1 and 32 is shut off. In the drawing, reference numeral 46 denotes a spring for holding the spool at the neutral position, and the spool 24 is moved against this spring. 47 and 48 are overload relief valves. A main supply passage 60 formed in the main body 23 is connected to the supply passage 39 via a load check valve 61, and the main supply passage 60 directly communicates with a main supply passage 60 a of the second direction switching valve 22. Then, pressure oil is supplied from the hydraulic pump P. The second directional control valve 22 has the same configuration as a normal directional control valve, and the spool 24a is moved leftward or rightward from the neutral position shown in FIG.
The pressure oil is supplied to 8a or 44a, and the predetermined cylinder 9a is extended or contracted. The other configuration of the above-described discharge passage 53a has almost no relation to the present invention, and thus the description thereof is omitted. The first directional control valve 21 which is the directional control valve for the arm constructed as described above moves to the left in the drawing when a hydraulic signal is given from the remote control valve to the pilot section 25, for example, and the annular groove is formed. 55 connects the supply / discharge passage 38 to the discharge passage 37
And the enlarged portions 30, 31, and 32 are shut off from each other, and the annular groove 58 connects the supply passage 39 to the supply / discharge passage 44. As a result, the pressure oil from the pump P
The load check valve 61 is pushed open from the main supply passage 60 to supply the supply passage 39, the enlarged portion 33, the annular groove 58, and the enlarged portion 3.
4. The air is supplied to the rod-side pressure chamber 11 of the arm cylinder 9 through the supply / discharge passage 44 and the pipe 12. At the same time, the oil in the head-side pressure chamber 10 is discharged to the tank through the pipe 8, the supply / discharge passage 38, the enlarged portion 28, the annular groove 55, the enlarged portion 27, and the discharge passage 37. Therefore, the cylinder 9 performs a contracting operation. On the other hand, on the contrary, the pilot unit 2
When the hydraulic signal is applied to the spool 6, the spool 24 moves rightward in the drawing, and the annular groove 55 moves the supply / discharge passage 38 into the supply passage 39.
And the enlarged portions 30, 31, and 32 are shut off from each other, and the annular groove 58 connects the supply / discharge passage 44 to the discharge passage 45. As a result, the pressure oil from the pump P
Supply from the main supply passage 60 to the head side pressure chamber 10 of the arm cylinder 9 through the load check valve 61, the supply passage 39, the enlarged portion 29, the annular groove 55, the enlarged portion 28, the supply / discharge passage 38, and the pipe 8. Will be done. At the same time, the oil in the rod side pressure chamber 11 reaches the pipe 12, the supply / discharge passage 44, the enlarged portion 34, the annular groove 58, the enlarged portion 35, and the discharge passage 45, and a part of the oil is discharged via the throttle 52. The passage 53 is discharged to the tank through the discharge passage 53a of the adjacent second directional control valve 22, and most of the other oil is boosted by the presence of the throttle 52, and pushes the check valve 51 open to open the regeneration passage 50 , The oil is supplied to the supply passage 39 through the enlarged portion 33, merges with the pressure oil from the pump P, and is supplied to the cylinder 9. That is,
The pressure oil discharged from the cylinder 9 is recycled. Accordingly, the cylinder 9 is supplied with a larger amount of pressure oil than the supply pressure oil from the pump P, and thus the cylinder 9 extends at a high speed. This regeneration is performed when the load on the cylinder 9 is relatively small, and when the load increases and the operating speed of the cylinder 9 becomes slower than the speed limited by the throttle 52,
Will not be done. Even if the directional control valve 21 is a directional control valve for a small construction machine and is small, the regeneration passage 50 is
Since it is formed not in the spool but in the main body 23 of the first directional control valve 21 as in the conventional case, the passage cross-sectional area can be formed larger than when it is provided in the spool. Therefore, the pressure loss at the time of regeneration is greatly reduced as compared with the conventional art, and the regeneration rate is improved. According to the present invention, since the regeneration passage is not provided in the spool but is provided in the directional control valve body, the passage cross-sectional area can be made large and the regeneration rate can be improved. Can be

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional front view of a first directional control valve according to an embodiment of the present invention. FIG. 2 is a vertical sectional front view of a second directional control valve of the embodiment. FIG. 3 is a vertical sectional front view of a main part of a directional control valve having a conventional regeneration circuit. [Description of Signs] 9 Arm cylinder 11 Rod side pressure chamber 21 First directional switching valve 22 Second directional switching valve 23 Main body of first switching valve 24 Spool of first switching valve 39 Supply passage 44 Supply / discharge passage 45 Discharge passage Reference numeral 50: regeneration passage 51, check valve 52, throttle 53a, discharge passage of the second direction switching valve

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) E02F 9/22 F15B 11/00 F15B 11/04

Claims (1)

(57) [Claims] [Claim 1] A first for supplying and discharging pressure oil to and from an arm cylinder
In a switching valve in which a directional switching valve and another second directional switching valve are connected in series, a pump is provided so as to substantially along a supply / discharge passage of the first directional switching valve connected to a rod-side pressure chamber of the arm cylinder. A regeneration passage connected to a supply passage is provided in the main body of the first direction switching valve, and a discharge passage connected at the time of a discharge operation of the supply / discharge passage is connected to the regeneration passage, and the first direction switching is performed.
A switching valve having a regeneration function for an arm, wherein a check valve is provided in a regeneration passage provided in a valve body, and the discharge passage is connected to a discharge passage of the second direction switching valve via a throttle.