WO2002055889A1

WO2002055889A1 - Hydraulic control circuit of working machine

Info

Publication number: WO2002055889A1
Application number: PCT/JP2001/011006
Authority: WO
Inventors: Tetsuya Yoshino; Yoshiyuki Shimada
Original assignee: Shin Caterpillar Mitsubishi Ltd.
Priority date: 2001-01-09
Filing date: 2001-12-14
Publication date: 2002-07-18
Also published as: JP2002206510A; JP3794927B2

Abstract

A hydraulic control circuit, comprising a boom cylinder for vertically moving a boom, a control valve for controlling the supply and discharge of pressure oil to and from the boom cylinder, and a regenerative circuit for supplying a part of the discharged oil from the head side oil chamber of the boom cylinder to the rod side oil chamber, wherein a discharge valve path (15d) for performing the discharge of oil from the head side oil chamber (8a) of the boom cylinder (8) to an oil tank (13) when the boom is lowered is provided in a second boom section control valve (15) and the discharge valve path is opened and closed based on the selection of a boom lowering speed selector switch (22), whereby a boom lowering speed can be varied according to the type of a work and the skill of an operator.

Description

Description Hydraulic control circuit for work machine

The present invention belongs to the technical field of a hydraulic control circuit of a working machine such as a hydraulic shovel used for various construction work, civil engineering work, and the like. Background art

In general, this type of working machine is designed to supply heavy objects to a weight holding side oil chamber and to supply a non-weight holding side oil chamber, for example, a boom cylinder for moving a boom mounted on a hydraulic excavator up and down. There is a hydraulic cylinder equipped with a hydraulic cylinder that moves up and down when oil is discharged from the cylinder and moves down when oil is supplied to the non-weight holding oil chamber and oil is discharged from the weight holding oil chamber.

As an example of such a hydraulic cylinder hydraulic control circuit, FIG. 3 shows a hydraulic control circuit of a brake cylinder provided in a hydraulic excavator. In FIG. 3, reference numeral 8 denotes a brake cylinder, 11, 1 and 1. 2 is the first and second hydraulic pump, 13 is the oil tank, and 14 is the first hydraulic pump 11 The first boom control valve that controls the supply and discharge of hydraulic oil to the cylinder 8 using the hydraulic oil supply source 11 Reference numeral 15 denotes a second boom control valve for controlling the supply of pressurized oil to the brake cylinder 8 using the second hydraulic pump 12 as a pressurized oil supply source, and 16 denotes another hydraulic pressure such as a bucket cylinder provided on a hydraulic shovel. A control valve 17 for the actuator is provided, and 17 is a pilot valve for outputting pilot pressure to the ascending and descending pilot lines E and F based on the operation of the operation lever 18 for the boom. A is a head-side line connecting the control valves 14 and 15 for the first boom and the second boom to the head-side oil chamber 8a of the boom cylinder 8, and B is a line for the first boom. A port side line connecting the control valve 14 to the port side oil chamber 8 b of the cylinder cylinder 8, and D is a regeneration line connecting the above head side line A and the rod side line B. In the regeneration line D, a regeneration valve 19 and a check valve 21 are provided. In this case, when the operation lever 18 for the boom is moved to the lower side, the control valve 14 for the boom and the valve 19 for regeneration are switched by the pilot pressure output from the pilot valve 17 to the lower pilot line F. You. As a result, the pressure oil from the first hydraulic pump 11 is supplied to the port-side oil chamber 8 b of the boom cylinder 8 via the first boom control valve 14, while the head-side oil chamber The oil discharged from 8a is discharged to the oil tank 13 via the first boom control valve 14 and supplied to the load side oil chamber 8b via the regeneration valve 19 and the check valve 21. It is being done. In other words, when the pressure of the head side line A is higher than the pressure of the head side line B when the boom is lowered, the oil discharged from the head side oil chamber 8a is used as reclaimed oil. The load-side oil chamber 8b can be supplied to the load-side oil chamber 8b. In this way, the load-side oil chamber 8b is supplied with pressure oil of the first hydraulic pump 11 supplied from the first boom control valve 14. As a result, the regenerating oil is supplied, and the operating speed of the beam cylinder 8 can be increased without the load side oil chamber 8b being in a reduced pressure state. Also, during a combined operation of another hydraulic actuator (eg, a bucket cylinder) using the first hydraulic pump 11 as a hydraulic oil supply source and the boom lowering, the excess pump flow obtained by the reclaimed oil is used for another hydraulic pump. Since the supply can be performed overnight, it is possible to suppress a decrease in the working speed of the other hydraulic actuator during the combined operation, thereby contributing to an improvement in the working efficiency.

By the way, in the prior art, in order to improve the working efficiency as much as possible, the amount of the regenerated oil from the cylinder head side oil chamber to the rod side oil chamber is increased so that the cylinder speed is set to be high. However, with this setting, there is a problem that the speed is too fast to operate when performing a work requiring fine operation or when the operator is a beginner. On the other hand, if the amount of regenerated oil is set to be small so that it can be easily operated by a fine operation or a beginner, there is a problem that the effect of providing the regenerating circuit is reduced and the working efficiency is reduced. Had a problem that the present invention was trying to solve

Disclosure of the invention

The present invention has been made in view of the above-described circumstances, and aims to solve these problems. A heavy object that is created and movable up and down is moved up by supplying oil to the weight holding side oil chamber and discharging oil from the weight non-holding side oil chamber, A hydraulic cylinder that expands and contracts so as to be moved down by oil supply and oil discharge from the weight holding side oil chamber, and controls pressure oil supply and discharge to the weight holding side oil chamber and the weight non-holding side oil chamber of the hydraulic cylinder. In a hydraulic control circuit for a working machine comprising a control valve and a regeneration circuit for supplying oil discharged from the weight holding side oil chamber to the weight non-holding oil chamber, the hydraulic control circuit includes: A discharge oil passage is provided for flowing the oil discharged from the oil chamber to the oil tank without passing through the control valve. By controlling the opening and closing of valve means arranged in the discharge oil passage, the oil from the weight holding side oil chamber to the oil tank is controlled. The oil discharge flow rate can be increased or decreased.

In this way, by increasing or decreasing the oil discharge flow from the weight holding side oil chamber to the oil tank, it is possible to change the descending speed of the heavy object according to the work content, the skill of the operator, and the like. As a result, workability and operability are improved. The present invention also provides an oil supply to the weight holding side oil chamber and an oil discharge from the weight non-holding side oil chamber to move the heavy object movable up and down to supply the oil to the weight non-holding side oil chamber and the weight. Hydraulic cylinder that expands and contracts so as to move down by oil discharge from the holding oil chamber, and pressurized oil supply to the weight holding oil chamber and non-weight holding oil chamber of the hydraulic cylinder using the first hydraulic pump as the source of pressure oil A first control valve for controlling discharge, a second control valve for controlling supply of pressurized oil to a weight holding side oil chamber of a hydraulic cylinder using a second hydraulic pump as a source of pressurized oil, and In a hydraulic control circuit for a working machine comprising a regeneration circuit for supplying discharged oil to a non-weight holding side oil chamber, the second control valve includes: A discharge valve channel to flow to the The opening and closing control allows the flow rate of oil discharged from the oil chamber on the weight holding side to the oil tank to be increased or decreased.

In this way, the second control valve is used to increase or decrease the oil discharge flow rate from the oil chamber on the weight holding side to the oil tank, so that the weight can be adjusted in accordance with the work content, skill of the operation, etc. Since the lowering speed of the object can be changed, workability and operability are improved, and the members can be shared. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a hydraulic excavator.

FIG. 2 is a hydraulic control circuit diagram showing an embodiment of the present invention.

FIG. 3 is a hydraulic control circuit diagram showing a conventional example. BEST MODE FOR CARRYING OUT THE INVENTION

Next, embodiments of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a hydraulic excavator, and the hydraulic excavator 1 includes a lower traveling body 2 of a crawler type, an upper revolving body 3 rotatably supported by the lower traveling body 2, and an upper revolving body 3 And a boom 5 which is supported by the upper revolving unit 3 so as to be able to swing up and down, and a front end of the boom 5. A stick 6 that is supported to be able to swing back and forth, a packet 7 that is supported to be able to swing back and forth at the tip end of the stick 6, a boom cylinder for causing these booms 5, sticks 6, and buckets 7 to swing. The basic configuration, such as comprising a member device such as 8, a stick cylinder 9, a bucket cylinder 10, etc., is the same as the conventional one.

Now, FIG. 2 shows a hydraulic control circuit for the above-mentioned cylinder cylinder 8. In FIG. 2, 11 and 12 are first and second hydraulic pumps, 13 is an oil tank, and 14 is an oil tank. Reference numerals 15 and 15 denote control valves for the first and second booms described later. Reference numeral 16 denotes a packet control valve, and the bucket control valve 16 is provided in parallel with the first boom control valve 14. The control valves provided in parallel with the first and second boom control valves 14 and 15 are, in addition to the bucket control valve 16, various hydraulic actuators provided on the hydraulic excavator 1. However, they are omitted in FIG. Further, in FIG. 2, A is a head side line connecting the control valve 14 for the first boom and the control valve 15 for the second boom with the head side oil chamber 8a of the boom cylinder 8, B is a load side line connecting the first boom control valve 14 to the load side oil chamber 8b of the pump cylinder 8, and D is a regeneration line connecting the head side line A and the rod side line B. Line.

The above-mentioned beam cylinder 8 supplies pressure oil to the head-side oil chamber 8 a and the rod-side oil chamber. The boom 5 is extended by oil discharge from 8b and moved up, and the boom 5 is moved down by compressed oil supply to the rod-side oil chamber 8 and oil discharge from the head-side oil chamber 8a. In this case, the head side oil chamber 8a corresponds to the weight holding side oil chamber of the present invention by holding the weight of the front attachment 4, and has a mouth opening. The oil chamber 8b on the outlet side corresponds to the oil chamber on the weight non-holding side of the present invention.

Further, the first boom control valve 14 includes ascending and descending pilot ports 14a and 14b, and a pilot port input to these pilot ports 14a and 14b. It is composed of a spool valve whose opening degree of the supply and discharge valve paths 14 c to 14 f described later is adjusted by pressure. In other words, the control valve 14 for the first boom is located at the neutral position N when the pilot pressure is not input to both the pilot ports 14 a and 14 b, and supplies the hydraulic oil to the boom cylinder 8. No discharge is performed, but when the pilot pressure is input to the rising-side pilot port 14a, it is displaced to the rising-side position X, and the hydraulic oil from the first hydraulic pump 11 passes through the head-side line A. Open the supply valve line 14c for supplying to the head-side oil chamber 8a of the boom cylinder 8, and discharge the oil from the mouth-side oil chamber 8b via the rod-side line B. The outlet valve 14d for flowing into the tank 13 is opened. Further, the control valve 14 for the first boom is displaced to the lower position Y by the input of the pie port pressure to the lower pilot port 14 b, and the pressure from the first hydraulic pump 11 is changed. Open the supply valve line 14 e for supplying oil to the inlet-side oil chamber 8 b via the load-side line B and open the head-side oil chamber 8 a to the head-side line. A discharge valve path 14f for flowing the oil discharged to A to the oil tank 13 via the restrictor 14g is provided. Here, the oil discharge from the head side oil chamber 8a of the first boom control valve 14 at the descending position Y to the oil tank 13 is performed by a throttle 1 provided in the discharge valve path 14f. The oil discharge flow rate of the discharge valve line 14f is set to a flow rate necessary to obtain a slow boom lowering speed suitable for performing a fine operation. I have.

On the other hand, the second boom control valve 15 has ascending-side and descending-side pilot ports 15a and 15b, and a pilot port input to these pilot ports 15a and 15b. The amount of opening of the supply and discharge valve paths 15c and 15d described later is adjusted by the pressure. It consists of a spool valve. In other words, the control valve 15 for the second boom is located at the neutral position N when the pilot pressure is not input to both the pilot ports 15a and 15b, and the hydraulic oil for the pump cylinder 8 No supply / discharge is performed, but when the pilot pressure is input to the rising pilot port 15a, it is displaced to the rising position X to open the supply valve passage 15c. The hydraulic oil from the second hydraulic pump 12 is supplied to the head side oil chamber 8a of the boom cylinder 8 via the head side line A. Also, the control valve 15 for the second boom is displaced to the descending position Y when the pilot pressure is input to the descending ^ J pilot port 15b to open the exhaust valve passage 15d. As a result, oil discharged from the head-side oil chamber 8a passes through the head-side line A, passes through a restrictor 15e provided in the discharge valve line 15d, and then flows into the oil tank 13 It is configured to flow to. Further, in FIG. 2, reference numeral 17 denotes a pilot pulp for a boom, which is composed of an ascending-side pilot valve 17A and a descending-side pilot valve 17B. The ascending and descending pilot valves 17A and 17B operate the boom operation lever 18 to the boom ascending and descending sides, respectively. It outputs each. Then, the pilot pressure output from the ascending pilot port pulp 17 A passes through the ascending pilot line E, and the ascending pilot port 14 a of the first and second boom control valves 14 and 15. Entered in 15 a. Further, the pilot pressure output from the descending ^ J pilot valve 17B is supplied to the descending pilot port 14b of the control valve 14 for the first boom via the descending pilot line F and to a regeneration port 14b for the regeneration described later. The signal is input to a pilot port 19 a of the valve 19 and is supplied to a speed switching valve 20 described later.

The regeneration valve 19 is disposed on the regeneration line D, and is constituted by a spool valve having a pilot port 19a. When the pilot pressure is not input to the pilot port 19a, the regeneration valve 19 is located at the closed position X where the regeneration line D is closed, but the pilot port 19a is connected to the pilot port 19a. When the pressure is input, the reproduction line D is switched to the open position Y that opens through the throttle 19b. In addition, 21 is a playback line. The check valve 21 is provided at D. When the pressure of the head side line A is higher than that of the rod side line B, the check valve 21 changes from the head side line A to the rod side line B. The flow of oil is allowed, but the flow in the opposite direction is prevented. Therefore, the regenerated pulp 19 is located at the open position Y, and the pressure of the head side line A is reduced to the rod side line. While the pressure is higher than B, oil in the line A on the head side flows through the line D for regeneration to the line B on the rotor side.

Further, the speed switching valve 20 is an electromagnetic two-position switching valve having a solenoid 20a, and when the solenoid 20a is not energized, the second boom control valve 15 The lower pilot port 15 of the second boom control valve 15 is located at the first position X and the lower pilot port 15 of the second boom is located at the first position X. Not input to b, but is switched to the second position Y where the pressure of the descending pilot line F is input to the descending pilot port 15b of the control valve 15 for the second boom by energizing the solenoid 20a. It is configured to

On the other hand, 22 is a boom lowering speed selection switch provided on the driver's seat, and the boom lowering speed selection switch 22 is electrically connected to a solenoid 20a of the speed switching valve 20. . The pump lowering speed selection switch 22 is capable of arbitrarily selecting "LOW" or "HI GH". The solenoid 20a of the speed switching valve 20 is When the boom lowering speed selection switch 2 2 is set to “L〇W”, power is not supplied, and when it is set to “HIGH”, power is supplied.

In the structure constructed as described above, when raising the pump 5 and operating the boom operation lever 18 to the rising side, the pipe pressure output from the rising side pilot valve 17 A will be increased. , 1st and 2nd boom control valves 14 and 15 Ascending side of pilot port Input to ports 14a and 15a, 1st and 2nd boom control valves 14 and 15 ascending side Switch to position X. As a result, the pressure oil of both the first and second hydraulic pumps 11 and 12 passes through the first and second boom control valves 14 and 15 to the head side oil of the boom cylinder 8. When the boom 5 is supplied to the chamber 8 a, the lifting operation of the boom 5 against the weight of the front desk fixture 4 can be performed strongly. On the other hand, when lowering the boom 5, if performing a fine operation or if the operator is a beginner, the boom lowering speed selection switch 22 is set to "L OW". When the boom lowering speed selection switch 22 is set to "LOW", the solenoid 20a of the speed switching valve 20 is not energized as described above, so that the speed switching valve 20 is not operated. It is located at the first position X where the pressure of the descending pilot line F is not input to the descending pilot port 15 b of the second boom control valve 15. In this state, when the boom operation lever 18 is moved to the lower side, the pilot pressure output from the lower pilot valve 17 B is applied to the lower pilot port 14 b of the first boom control valve 14 and to the regeneration port. Is input to the pilot port 19a of the control valve 19, the first boom control valve 14 is switched to the lower position Y, and the regeneration valve 19 is switched to the open position Y. On the other hand, the second boom control knob 15 is held at the neutral position Ν. As a result, the pressure oil from the first hydraulic pump 11 is supplied to the load side oil chamber 8 of the boom cylinder 8 via the first boom control valve 14 and the head side line Α When the pressure is higher than that on the port side line B, a part of the oil discharged from the head side oil chamber 8a is supplied to the rod side oil chamber 8 via the regeneration valve 19 and the check valve 21. It is supplied to b as recycled oil. The remaining oil discharged from the head-side oil chamber 8a is discharged to the oil tank 13 via the first boom control valve 14.

In other words, when set to “L OW”, the oil discharge from the head side oil chamber 8 a of the boom cylinder 8 to the oil tank 13 is performed by discharging the control valve 14 for the first boom. This is performed only through the valve path 14f, but the oil discharge flow rate of the discharge valve path 14f is set to a flow rate at which a slow boom descent speed can be obtained. 5 moves down slowly, improving operability when performing fine operations or when the operator is a beginner.

On the other hand, when lowering the boom 5, it is necessary to improve the work efficiency or to perform a work requiring a fast boom descent such as an excavation loading operation. Set to “HIGH”. As a result, the solenoid 20 a of the speed switching valve 20 is energized, and the speed switching valve 20 increases the pressure of the descending pilot line F by the second boom control valve 15. Switches to the second position Y input to the descending pilot port 15b. In this state, when the operation lever 18 for the boom is operated to the lower side, the pilot pressure output from the lower-side pilot valve 17 B will be lower than the control pulp 14 and 15 for the first and second booms. Descending pie port 14b, 15b and regeneration port 19 are input to pie port 19a, and the first and second boom control valves 14, 15 are moved to the down position. Switch to Y and switch regeneration valve 19 to open position Y. Thereby, the pressure oil from the first hydraulic pump 11 is supplied to the inlet side oil chamber 8 b of the boom cylinder 8 via the first boom control valve 14, and the head side line While the pressure of A is higher than that of the inlet side line B, part of the oil discharged from the head side oil chamber 8a is supplied to the rod side oil via the regeneration valve 19 and the check valve 21. Room 8b is supplied as reclaimed oil. The remaining oil discharged from the head side oil chamber 8a is discharged to the oil tank 13 via the first boom control valve 14 and the second boom control valve 15.

In other words, when set to “HIGH”, the oil discharge from the oil chamber 8 a on the head side of the boom cylinder 8 to the oil tank 13 causes both the first and second boom control valves 1. The control valve for the second boom is compared with the case where only the control pulps for the first boom 14 described above are performed through the discharge valve lines 14f and 15d for the discharge of the four and fifteen. The amount of oil discharge increases by 15 and the oil discharge from the head side oil chamber 8a is made faster, so that the lowering operation of the boom 5 is performed at a high speed. Can be done.

As described above, in the present embodiment, when the boom 5 is lowered, if the boom lowering speed selection switch 22 is set to “HIGH”, the oil from the head-side oil chamber 8 a of the boom cylinder 8 is discharged. If the oil discharge flow rate to the tank 13 increases and the descent speed of the boom 5 increases, and the boom descent speed selection switch 22 is set to “L 0 W”, the oil from the head side oil chamber 8a The oil discharge flow rate to the tank 13 decreases, and the descent speed of the boom 5 decreases. As a result, the lowering speed of the boom 5 can be arbitrarily selected according to the work content and the skill of the operator, thereby improving operability and workability.

Moreover, in this case, the oil discharge flow rate from the head-side oil chamber 8a to the oil tank 13 is increased or decreased by using the second boom control valve 15. The second boom control valve 15 is operated to supply the hydraulic oil of the second hydraulic pump 12 to the boom cylinder to the head side oil chamber 8a when the boom 5 is raised. By having two functions, the members can be shared and contribute to cost reduction. Further, since the second boom control valve 15 is a spool valve whose opening is adjusted by the input pilot pressure, good operability corresponding to the amount of operation of the boom operation lever 18 can be obtained. Can be.

The present invention is, of course, not limited to the above-described embodiment. The hydraulic cylinder for moving a heavy object up and down is not limited to a boom cylinder provided in a hydraulic shovel, but may be provided in various work machines. The present invention can be appropriately implemented as needed for the hydraulic cylinder to be used. Industrial applicability

The hydraulic control circuit of the working machine according to the present invention includes a control valve for controlling the supply and discharge of pressure oil to and from the oil chamber on the weight holding side of the hydraulic cylinder; A regeneration circuit for supplying the oil to the holding-side oil chamber, and an oil passage for discharging oil from the weight-holding oil chamber to the oil tank without passing through the control valve. By controlling the opening and closing of the valve means arranged in the oil passage, the oil discharge flow rate from the oil chamber on the weight holding side to the oil tank can be increased or decreased. As a result, by increasing or decreasing the oil discharge flow rate from the weight holding side oil chamber, it is possible to change the descent speed of the heavy object in accordance with the work content, the skill of the operation, etc. Operability is improved.

Further, the hydraulic control circuit of the working machine according to the present invention performs pressure oil supply / discharge control to the weight holding side oil chamber and the weight non-holding side oil chamber of the hydraulic cylinder using the first hydraulic pump as a pressure oil supply source. A first control valve, a second control norb for controlling the supply of pressure oil to the weight holding side oil chamber by using the second hydraulic pump as a pressure oil supply source, and a non-weight holding side oil for discharging oil from the weight holding side oil chamber. A regeneration circuit for supplying the oil to the oil chamber, and a discharge valve path for allowing the oil discharged from the weight holding side oil chamber to flow into the oil tank. The discharge valve path is provided in the second control valve. By controlling the opening and closing of the oil, the oil discharge flow rate from the oil chamber on the weight holding side to the oil tank can be increased or decreased. As a result, the weight holding side is By increasing / decreasing the oil discharge flow rate from the oil chamber, it is possible to change the descent speed of heavy objects according to the work content, the skill of the operator, etc., thereby improving workability and operability. It is possible to use the same material.

Claims

Sought

1. The vertically movable heavy object is moved up by the oil supply to the weight holding side oil chamber and the oil coming out of the weight non-holding side oil chamber, and the oil supply to the weight non-holding side oil chamber and the weight holding side oil chamber. A hydraulic cylinder that expands and contracts so as to be moved downward by oil discharge from the hydraulic cylinder, a control knob that controls the supply and discharge of pressurized oil to the weight holding side oil chamber and the weight non-holding side oil chamber of the hydraulic cylinder, And a regeneration circuit for supplying oil discharged from the chamber to the non-weight holding oil chamber. A hydraulic control circuit for a working machine comprising: A configuration in which a discharge oil passage that flows to the oil tank without passing through a control valve is provided, and the flow rate of oil discharge from the oil chamber on the weight holding side to the oil tank can be increased or decreased by controlling the opening and closing of valve means arranged in the discharge oil passage. Working machine hydraulic control Your circuit.

2. Move the vertically movable heavy object up and down with the oil supply to the weight holding side oil chamber and the oil from the weight non-holding side oil chamber to supply oil to the weight non-holding side oil chamber and the weight holding side oil chamber. Hydraulic cylinder that expands and contracts so that it moves down with oil discharged from the hydraulic pump, and hydraulic oil supply and discharge to the weight holding side oil chamber and the weight non-holding side oil chamber of the hydraulic cylinder using the first hydraulic pump as the hydraulic oil supply source A first control valve for performing control, a second control valve for performing pressure oil supply control to the weight holding side oil chamber of the hydraulic cylinder using the second hydraulic pump as a pressure oil supply source, and a second control valve for controlling pressure from the weight holding side oil chamber. In a hydraulic control circuit for a working machine comprising a regeneration circuit for supplying discharged oil to a non-weight holding side oil chamber, the second control valve may be configured to supply the discharged oil from the weight holding side oil chamber to an oil tank. A discharge valve channel is provided for the exhaust valve, and the opening and closing of the discharge valve channel is controlled. A hydraulic control circuit for a working machine, characterized in that the oil discharge flow rate from the weight holding side oil chamber to the oil tank can be increased or decreased.