JPS62264221A - Switch valve for oil-pressure shovel - Google Patents

Abstract

PURPOSE:To expand the function of a switch valve by using a system in which when a switch valve for slewing is switched, slewing pilot pressure for operating slewing motor moves a piston in an arm spool, and thereby return oil path from an arm cylinder is throttled. CONSTITUTION:When concurrently performing the rotation of a slewing motor and the extending action of an arm cylinder 4, pressure oil from an oil-pressure pump opens a check valve 22 in a slewing switch valve 5, and thereby the motor 3 is turned through a bridge oil path 47 and a port B. At the same time, the pressure oil partly acts on a piston 42 through a slewing pilot pressure oil path 26, a slewing pilot pressure-introducing port 37, a pilot oil path 27, the slewing pilot pressure-introducing port 38 for arm switching valve 6, the notched hole 45 of arm spool 36, and an oil chamber 44 on the back side of the piston. The piston 41 then moves forwards to throttle the opening area of the notch hole 43. The flow rate in the arm cylinder 4 is reduced and oil pressure from the pump 7 is supplied through the switch valve 5 to the motor 3 to increase the slewing force of the motor 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an arm switching valve and a swing switching valve for a hydraulic excavator.

BACKGROUND OF THE INVENTION Work attachments (not shown) such as booms, arms, and packets are attached to the front part of the upper revolving body of a hydraulic excavator to perform various excavation operations. Among these, there are swing pressing excavation in which the side of the packet is pressed against the inclined wall surface and the wall surface is excavated vertically, and arm diagonal pull grading, both of which involve simultaneous swing and arm operation. Therefore, in swing push excavation, if the swing force is small, the packets will escape in any direction and the inclined wall surface cannot be excavated vertically. Therefore, when operating the swing and arm simultaneously on a hydraulic excavator, the swing priority system is used. It has been adopted.

FIG. 7 is a hydraulic circuit diagram of a prior art swing priority system. In FIG. Arm cylinder, 5° is a swing switching valve, 6′ is an arm switching valve, 7 is a hydraulic pump, 8 is a swing switching valve 5° is a shuttle valve installed in the middle of the oil passage that communicates the left and right pilot pressure receiving parts, 9 is a It is a pilot pump.

In the hydraulic circuit shown in FIG. 7, the operating functions for simultaneous rotation and arm operation will be described. For example, the swivel remote control valve 1 is operated to the A position, and the arm remote control valve 2 is simultaneously operated to the Open position. Then, the pilot pressure from the swing remote control valve 1 passes through the pilot oil passage 10 to the swing switching valve 5.
It acts on the right pilot pressure receiving pressure part of ゛ and switches the swing switching valve 5゛ to position C, and the biloft pressure from the arm remote control valve 2 passes through the pyro throat oil passage 11 to the right pilot pressure receiving pressure of the arm switching valve 6''. to switch the arm switching valve 6'' to two positions. At the same time, the pressure oil discharged from the hydraulic pump flows through oil path 12, check valve 13, and oil path 1.
4.15. Oil is sent to the swing motor 3 through the check valve 16 and the swing switching valve 5' position C, and the swing motor 3 is rotated. On the other hand, since the arm cylinder 4 and the swing motor 3 are connected in parallel, the pressure oil discharged from the hydraulic pump 7 flows through the check valve 13, the oil passage 17, the arm switching valve 6', and the oil passage 18. The oil is then sent to the head side of the arm cylinder 4, and the arm cylinder 4 is extended. A portion of the pilot pressure oil acting on the right pilot pressure receiving part of the swing switching valve 5° passes through the shuttle valve 8 and the oil passage 19 to the variable restrictor 20 in the two-position section of the arm switching valve 6''. Therefore, the return oil circuit from the arm cylinder 4 piston rod side is connected to the variable throttle section 2 in the two-position section of the arm switching valve 6°.
At step 1, the oil passage is constricted. For that purpose, arm cylinder 4
The pressure on the head side increases, but the amount of oil sent decreases, so the pressure oil discharged from the hydraulic pump 7 is transferred to the check valve 13 and the oil path 14.
．． 15, the check valve 16, and the swing switching valve 5' in position C, a large amount is supplied to the swing motor 3, and the swing force increases.

Problems to be Solved by the Invention When a hydraulic excavator simultaneously operates its swing and arm, the prior art employs the above-mentioned swing priority system to increase the swing force. Therefore, in FIG. 7, the variable restrictor 20 in the two-position section of the arm switching valve 6'
The viroft pressure signal acting on the swivel remote control valve 1
The viroft secondary pressure is used.

However, some models of hydraulic excavators, such as small hydraulic excavators, do not employ a remote control valve operation type but are equipped with a so-called direct pull operation type switching valve using a direct lever or link. Therefore, the pilot secondary pressure from the remote control valve as in the prior art shown in FIG. 7 cannot be used.

Therefore, it is an object of the present invention to improve the above-mentioned points and provide an arm and a swing switching valve that can be used in a direct pull operation type and a remote control valve operation type.

Means for Solving the Problems The means of the present invention taken to solve the above problems are as follows: (a) A piston sliding chamber in which a piston is inserted into the spool of the arm switching valve is provided, and (b) When the arm cylinder extension operation is switched. , communicates the piston mouth/throat side of the arm cylinder with the return (mountain passage) through the front side of the piston sliding chamber and its horn, and 3. The swing operating pressure in the swing switching valve is controlled by the switching operation of the swing spool. is derived to act on the oil chamber on the rear side of the piston in the arm spool of the arm cutter 1^ valve, and 2. The piston in the arm spool is configured to be able to narrow down the opening area of the notch hole on the front side of the piston sliding chamber. .

Operation A: When the arm switching valve is in the neutral position, no hydraulic oil flows into the piston sliding chamber, so even if the swing switch is activated, the swing operation pilot pressure will only act on the rear oil chamber of the piston in the arm spool, and the swing will be activated. is unrelated.

B. Even if the arm switching valve is switched, if the swing switching valve is in the neutral position, the swing operation pilot pressure will not act on the piston in the arm spool, so the piston in the arm spool will not operate the throttling function. The amount of oil returned from the piston rod side of the cylinder will not be reduced due to throttling.

C. When the rotation of the swing motor and the extension of the arm cylinder are operated simultaneously, the swing operation biloft pressure acts on the rear chamber of the piston in the arm spool, so the piston in the piston sliding chamber moves forward and increases the opening area of the notch hole in the arm spool. Refine.

2. On the other hand, since the return oil from the arm cylinder passes through the narrowed notch hole, the flow rate to the arm cylinder decreases. Therefore, a large amount of the pressure oil discharged from the hydraulic pump is supplied to the swing motor via the swing switching valve, and the swinging force of the swing motor increases.

Example Hereinafter, the present invention will be described in detail based on embodiments.

FIG. 1 is a hydraulic circuit diagram having a swing and arm switching valve according to the present invention, where 3 is a swing motor, 4 is an arm cylinder, 5 is a direct pull operation swing switch valve, and 6 is a direct pull operation arm switch valve. , 7 is a hydraulic pump, 22 is a check valve for the swing switching valve 5, 23 is a check valve for the arm switching valve 6, 24 is a piston throttle part located in the arm switching valve 6, 2
5 is the center bypass oil passage of the swing switching valve 5, 26 is the swing pilot pressure oil passage, and 27 is the swing switching valve 5 and the arm switching valve 6.
28 is a relief valve for the swing motor 3, 29 is a check valve for the swing motor 3, 30 is a boost check valve, 31 is a check valve, 32 is a prime mover for driving the hydraulic pump 7, 33 is a main oil Road relief valve, 3
4 is an oil tank.

FIG. 2 is a detailed cross-sectional view when the swing switching valve 5 is in the neutral position and the arm switching valve 6 is switched to the arm cylinder extension operation. In FIG. 0, 35 is a swing spool in the swing switching valve 5; 36 is an arm spool in the arm switching valve 6, 37 is a swing pilot pressure derivation port of the swing switching valve 5, 38 is a swing biloft pressure introduction boat in the arm switching valve 6, 39 is a bridge oil passage in the arm switching valve 6, 40 41 is a piston slidably inserted into the piston sliding chamber 40; 42 is a piston sliding chamber provided in the arm spool 36;
．． 43 is a notched hole communicating from the outer circumference of the arm spool 36 to the front side of the piston sliding chamber 40, 44 is a piston rear oil chamber, 45 is a notch hole communicating from the outer circumference of the arm spool 36 to the piston rear oil chamber 44, 46 is a return boat of the arm switching valve 6, A and B are ports for connecting the oil passage from the swing switching valve 5 to the swing motor 3, and C and D are ports from the arm switching valve 6 to the head side of the arm cylinder 4 and the piston rod side. Each of these is a boat for connecting oil lines.

Therefore, as shown in FIG. 2, when the arm spool 36 in the arm switching valve 6 is moved in the direction of the arrow without switching the swing switching valve 5, the pressure oil discharged from the hydraulic pump 7 is transferred to the bridge oil passage 39, the boat The oil is sent to the head side oil chamber of the arm cylinder 4 through C.

On the other hand, the return oil from the piston rod side of the arm cylinder 4 is transferred to the boat rotor 1 arm spool 36 of the arm switching valve 6.
It returns to the oil tank 34 through the notch hole 42, the front side of the piston sliding chamber 40, the notch hole 43, and the return port 46.

It should be noted that since the rotation operating pressure does not act on the oil chamber 44 on the rear side of the piston in the arm spool 36, the return oil from the arm cylinder 4 is not subjected to a throttling action by the piston 41.

Next, based on FIGS. 1 and 3, the operating function of the switching valve of the present invention during simultaneous swing and arm operation will be described. When the swing motor rotates 3 times and the arm cylinder 4 extends at the same time, the pressure oil discharged from the hydraulic pump 7 flows through the swing switching valve 5.
The inner check valve 22 is opened, and the swing motor 3 is rotated through the bridge oil passage 47 and port B. At the same time, a part of the operating pressure oil of the swing motor 3 is supplied to the swing pilot pressure oil passage 26, the swing pilot pressure derivation port 37, the pilot oil passage 27, the swing pilot pressure introduction boat 38 of the arm switching valve 6, and the notch hole of the arm spool 36. 45, acts on the piston 42 via the piston rear oil chamber 44. Then, the piston 41 moves to the front side, and the opening area of the notch hole 43 on the front side of the piston sliding chamber 40 is narrowed down.
Since the flow rate of the arm cylinder 4 decreases, a large amount of the pressure oil discharged from the hydraulic pump 7 is supplied to the swing motor 3 via the swing switching valve 5, and the swinging force of the swing motor 3 increases.

Next, FIG. 4 shows another embodiment of the present invention, in which remote control valves 1 and 2 are arranged for operating the swing motor 3 and arm cylinder 4, respectively.

For this purpose, in the figure, the swing switching valve 48 and the arm switching valve 49 have pilot pressure receiving portions on the left and right sides, and are switched by the pilot pressure from the remote control valves 1 and 2, respectively. Therefore, the operating functions of the swing switching valve 4 and the arm switching valve 49 are the same as those of the swing switching valve 5 in FIG.
and arm switching valve 6.

FIG. 5 also shows another embodiment of the present invention, in which a spring is inserted into the arm spool of the arm switching valve. In FIG. 5, 50 is an arm switching valve, 51
is an arm spool, 52 is a piston slidably inserted into the arm spool 51, 53 is a return oil passage oil chamber in the arm spool 51, and 54 and 55 are return oil passage oil chambers 53 from the outer periphery of the arm spool 51. Leading notch hole, 56
57 is the piston front spring chamber, and 57 is the piston front spring chamber 56.
58 is a spring incorporated in the spring chamber 56 on the front side of the piston, 59 is an oil chamber on the rear side of the piston, and 60 is a notch that leads from the outer periphery of the arm spool 51 to the oil chamber 59 on the rear side of the piston. It's a hole. Note 3
4 is an oil tank, 38 is a rotating pilot pressure introduction boat, 3
Reference numeral 9 designates a bridge oil passage within the arm switching valve, and 46 represents a return oil pressure return oil passage from the arm cylinder 4.

Therefore, a hydraulic circuit diagram in which the arm switching valve 50 and the swing switching valve 5 having the above structure are arranged is shown in FIG. Therefore, the operating function of the arm switching valve 50 will be described based on FIGS. 5 and 6. When the swing switching valve 5 is switched to the water position and the arm switching valve 50 is switched to the t position and operated simultaneously, the pressure oil discharged from the hydraulic pump 7 is transferred to the check valve 22.
, rotates the swing morph 3 through the water position of the swing switching valve 5, and on the other hand, the check valve 23 and the arm switching valve 5
After reaching the 0 position, the arm cylinder 4 is extended. At the same time, a part of the operating pressure oil of the swing motor 3 is supplied to the swing pilot pressure derivation boat 37 of the swing switching valve 5 H position section, the pilot oil passage 27, the swing pilot pressure introduction boat 38 of the arm switch valve 50 S position section, and the arm spool. 51 through the notched hole 60 to the piston rear oil chamber 59
and moves the piston 52 forward. At this time, the spring 58 in the piston front spring chamber 56 is compressed, and a portion of the oil in the spring chamber 56 is sent to the external oil tank 34 via the drain oil path 57. Therefore, as the piston 52 moves forward, the shoulder of the piston 52 returns and narrows the opening area of the notch hole 55 of the oil passage chamber 53, so the flow rate of the arm cylinder 4 decreases and the flow rate to the swing motor 3 increases. , the turning force of the turning motor 3 increases. Note that when the swing switching valve 5 is returned to the neutral position, the swing pilot pressure does not act on the piston 52 in the arm spool 51, so the piston 52 moves rearward due to the spring force of the spring 58, and the notch hole 55 is fully opened. The return oil of the arm cylinder 4 is no longer subjected to the throttling action.

Effects of the Invention As mentioned above, in the hydraulic excavator switching valve of the present invention, a piston sliding chamber in which a piston is inserted is provided in the arm spool of the arm switching valve, and when the arm cylinder is extended, the piston rod side The return oil passes through the oil chamber on the front side of the piston sliding chamber in the arm spool and its notch hole, and returns to the return oil path. On the other hand, when the swing switching valve is operated, the swing operation pilot pressure is configured to act on the oil chamber on the rear side of the piston in the arm spool. For this purpose, if the swing and arm cylinder extension operations are operated simultaneously, the piston in the arm spool narrows the return oil path from the arm cylinder, reducing the amount of 2a and increasing the flow rate to the swing motor, thereby increasing the swing force of the hydraulic excavator. increase. In conventional technology, secondary pressure from a remote control valve was used to narrow down the return oil path from the arm cylinder, so for hydraulic excavators that do not use a remote control method, a swing priority system using a conventional switching valve is used. could not be adopted. However, in the present invention, when the swing switching valve is switched, the swing pilot pressure for operating the swing morph moves the piston in the arm spool, thereby narrowing the return oil path from the arm cylinder.

Therefore, the switching valve of the present invention enables a swing priority system during simultaneous swing and arm operation, regardless of whether the hydraulic cylinder is a direct pull operation type or a remote control valve operation type. Can be expanded.

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram including the switching valve of the present invention, FIGS. 2 and 3 are detailed cross-sectional views of the swing and arm switching valve, FIG. 4 is a hydraulic circuit diagram of another embodiment of the present invention, and FIG. 6 is a hydraulic circuit diagram of another embodiment of the present invention, and FIG. 7 is a hydraulic circuit diagram having a conventional switching valve. 3... Swivel motor 4... End cylinder 5.5°, 4
8...Swivel switching valve 6.6°...Arm switching valve 49.50...
...Arm switching valve 36.51...Arm spool 38...Swivel pilot pressure 4-person boat 4
1.52...Piston 42.43...Notched hole 45.54...Notched hole 55.60...Notched hole or more

Claims (1)

[Claims] In the switching valve in the hydraulic circuit of a hydraulic excavator, which controls the operation of various hydraulic actuators by switching the pressure oil discharged from the hydraulic pump, a piston sliding chamber with a piston inserted into the arm spool of the arm switching valve is installed, and the arm cylinder is extended. At the time of switching, the piston rod side of the arm cylinder and the return oil passage are communicated through the front side of the piston sliding chamber and its notch hole, and the swing operating pressure in the swing switching valve is derived by the switching operation of the swing spool. A hydraulic excavator characterized in that the piston in the arm spool of the arm switching valve acts on a rear side oil chamber of a piston in the arm spool, and is configured such that the piston in the arm spool can narrow down the opening area of a notch hole on the front side of the piston sliding chamber. Switching valve for use.