WO2002095240A1

WO2002095240A1 - Hydraulic control circuit for attachment in construction machine

Info

Publication number: WO2002095240A1
Application number: PCT/JP2002/003410
Authority: WO
Inventors: Hitoshi Iwasaki
Original assignee: Shin Caterpillar Mitsubishi Ltd.
Priority date: 2001-05-18
Filing date: 2002-04-04
Publication date: 2002-11-28
Also published as: JP2002339908A

Abstract

A hydraulic control circuit which can be altered easily when an attachment is replaced in a construction machine. The hydraulic control circuit is arranged such that both a second oil path L for supplying pressure oil of a second main pump (12) to a control valve (16) for attachment and a second pump control oil path M for flow rate control of the second main pump are opened/closed by switching a first changeover valve (33), and both a relief oil path Q for feeding oil of a first attachment oil path J to the tank (14) side and a discharge oil path P for feeding oil of a second attachment oil path K to the tank side are opened/closed by switching a second changeover valve (34).

Description

Hydraulic control circuit for equipment in the specification

The present invention belongs to the technical field of hydraulic control circuits for attachment in construction of hydraulic excavators and the like.

Background art

In addition, some hydraulic excavators and the like have various attachments, such as breakers and breaks, that can be attached and detached as work attachments, in addition to the normally used packets. In such a case, it is necessary to change the hydraulic control for the attachment according to the attachment to be mounted. In other words, the knitting attachments can be classified into four types as shown in FIG. 9, for example, in terms of hydraulic control. In FIG. 9, the first class of attachments suffices at the flow rate of the pump. Double-acting type (for example, a small breaker), the second attachment is a single-acting type (for example, a small breaker, etc.) that suffices for the flow rate of the pump, and the third class attachment is two pumps. Attachment of the fourth class is a double-acting type requiring a minute ^: (for example, breaking of ^ M), and a single-acting type requiring a flow rate of two pumps (for example, a large breaker) Therefore, for each of the first to fourth ^! Attachments, separate hydraulic pressure will be applied. For example, a hydraulic control circuit for such an arrangement as shown in FIG. 7 is known. In FIG. 7, reference numeral 10 denotes an attachment, and reference numerals 11 and 12 denote a first and a second. A main pump, 13 is a pipe pump, 14 is an oil tank, 16 is a valve control valve for controlling the supply and discharge of pressurized oil to the device 10, and 30 is an operating device for the device. 31 Pilot valve that outputs pilot pressure to control valve 16 for operation based on the operation of 1; 25, 26 are first and second negative controls Relief valve for control, 24 for control valve for second center bypass arranged upstream of relief valve for second negative control 26, J and K for control pulp for attachment 16 and equipment 10 The first and second oil passages for connecting the oil inlet / outlet ports 10a and 10b to the control valve for supplying hydraulic oil from the first main pump 11 to the control valve for attachment The first pump oil passage, L is the second pump oil passage for supplying the pressure oil from the second main pump 12 to the control valve 16 for attachment, and the M is output from the pilot port valve 30. The second pump control oil passage for supplying the pie port pressure to the pie port 24b of the control valve 24 for the second sensor bypass, Q is the first oil passage for the first joint J Is a relief oil passage through which oil flows through the relief valve 39 to the oil tank 14 side. Oil § evening Dzuchimento oil passage K is a discharge oil passage for supplying the oil tank 1 4 side. 40 is a first switching valve for opening and closing the second pump oil passage L, 41 is a second switching valve for opening and closing the second pump control oil passage M, and 42 is a third switching valve for opening and closing the relief oil passage Q. A switching valve 43 is a fourth switching valve for opening and closing the discharge oil passage P, and the first to fourth switching valves 40 to 43 are manually operated pole valves as shown in FIG. Have been. When the first switching valve 40 closes the second pump oil passage L, the pressure oil supplied to the attachment control valve 16 is only the pressure oil of the first main pump 11. When the first switching valve 40 opens, the hydraulic oil of both the first and second main pumps 11 and 12 is supplied to the control pulp 16 for attachment. In the state where the second switching valve 41 closes the second pump control oil passage M, the flow control of the second main pump 12 is not performed based on the operation of the attachment operating tool 31, By opening the second switching valve 41, the negative control of the second main pump 12 can be performed. Further, when the third and fourth switching valves 42 and 43 are closed, a double-acting valve is connected from the attachment control knob 16 via the first and second attachment oil passages K. Pressure oil can be supplied to the attachment in both directions, but by opening the third switching valve 42, the relief of the oil passage on the pressure oil supply side of the single-acting attachment (oil passage J for the first attachment) is activated. By opening the fourth switching valve 43, the back pressure of the single-acting attachment can be reduced. In addition, in FIG. 7, 17 to 23 are various oils provided in the hydraulic excavator. This is a control valve that controls the supply and discharge of pressure oil to the pressure actuator. Also, in Fig. 7, ① and ②, ② and ② are connected to each other. By the way, in the hydraulic control circuit of the equipment, in order to perform hydraulic control corresponding to each of the above-described first to fourth classification elements, all of the first to fourth switching valves are set to each ^! They need to be switched accordingly. In other words, as shown in Fig. 9 in Part 3, in the case of a double-acting attachment (first class) that requires only one pump, the first to fourth switching valves are switched to the closed side. In the case of a single-acting arrangement (second through), which is sufficient for the flow rate of the number of pumps, switch the first and second switching valves to the closed side, and switch the third and fourth switching valves to the open side. . In addition, the double-acting attachment (third 颁) that requires the flow rate of two pumps is equipped with a third and fourth directional control valve while switching the first and second directional control valves to the open side. To the closed side, and for single-acting attachments (fourth class) requiring two pumps, switch the first to fourth switching valves to the open side. become. However, every time the attachment is replaced, the operation of switching the four switching valves is complicated, or there is a problem that an error easily occurs, and there is a problem to be solved by the present invention. Furthermore, the leakage 3 switching valve is configured using a manual poll valve, but a high-performance ball valve with little leakage and small pressure loss is expensive and hinders cost reduction. There was also a problem to be tested.

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has been created for the purpose of solving these problems, and includes a hydraulically actuated actuator, and control of supply and discharge of hydraulic oil to the actuator. Attachment control valve for performing pressure control, a first pump oil passage for supplying pressure oil from the first and second pumps to the attachment control valve, and a first pump oil passage for supplying pressure oil from the first pump to the attachment control valve. A control circuit for supplying hydraulic oil from the second pump to the hydraulic control circuit for attachment to the control valve for unfavorable attachment; In providing the two pump oil passages and the second pump control oil passage for controlling the flow rate of the second pump, opening and closing both the second pump oil passage and the second pump control oil passage are performed. It is configured such that it can be performed based on the switching operation of one switching means. In this manner, by switching one switching means, only the pressure oil from the first pump is supplied to the attachment, and the pressure oil from both the first and second pumps is supplied to the attachment. Since the hydraulic control circuit can be changed, the circuit can be easily changed and errors can be suppressed. The present invention also relates to an attachment which is operated by hydraulic pressure, a control valve for an attachment which controls supply and discharge of pressurized oil to the attachment, and a connection between the control vanolev for the attachment and an oil outlet of a frf self-attachment. An oil pressure control circuit having a first and a second oil passage for an operation, the oil in the oil passage for the first attachment being supplied to the oil pressure control circuit for the attachment via a relief valve. Opening and closing of the relief oil passage and the discharge oil passage to provide a relief oil passage for flowing oil to the tank side and a discharge oil passage for flowing oil from the second alignment oil passage to the tank side. Can be performed based on the switching operation of one switching means. In this way, by switching one switching means, the hydraulic control circuit for supplying the hydraulic oil to the double-acting attachment and supplying the hydraulic oil to the single-acting attachment can be formed. By being able to make the change, the circuit change becomes easy and the occurrence of errors can be suppressed. Further, the present invention provides a hydraulically operated attachment, an alignment control valve for controlling hydraulic oil supply and discharge to the alignment, and a connection between the alignment control valve and an oil outlet of the alignment. First and second pump oil passages, first and second pumps, and a first pump oil passage for supplying pressure oil from the first pump to the attachment control valve. A hydraulic pump control circuit, comprising: a second pump oil passage for supplying pressure oil from a second pump to the control hydraulic control circuit; The oil in the second pump control oil passage for controlling the flow rate of the oil and the oil in the first treatment oil passage When providing a relief oil passage for flowing oil to the tank side and a discharge oil passage for flowing oil of the second attachment oil passage to the tank side, the second pump oil passage and the second pump are controlled based on the switching operation of the first switching means. The opening and closing of both oil passages of the oil passage for use is performed, and the opening and closing of both oil passages of the relief oil passage and the discharge oil passage can be performed based on the switching operation of the second switching means. In this way, by switching the first switching means, the case where only the pressure oil from the first pump is supplied to the attachment and the case where the pressure oil is supplied from both the first and second pumps The hydraulic control circuit can be changed as follows, and the pressure can be supplied to the double-acting element by switching the second switching means: Since the hydraulic control circuit can be changed, the circuit can be easily changed and the occurrence of a mistake can be suppressed. In these devices, the second pump control oil passage is a pie port oil passage for supplying pie port pressure to the flow control norb of the second pump based on the operation of the attachment operating tool; The second pump oil passage is opened and closed by a second pump oil passage opening / closing valve that is operated by the pilot pressure supplied to the oil pump control oil passage, and the second pump oil passage and the second pump are opened. The switching means for opening and closing both oil passages of the control oil passage can be constituted by a switching valve for opening and closing the second pump control oil passage. In addition, the relief oil passage is opened and closed by a relief oil passage opening and closing valve operated by the nozzle port pressure, and the discharge oil passage is opened and closed by a discharge oil passage opening and closing valve operated by the pilot pressure. The switching means for opening and closing both the relief oil passage and the discharge oil passage can be constituted by a switching valve for switching the opening and closing of the pilot port pressure supply oil passage to the two on-off valves. Furthermore, by configuring the switching means with a manual spool valve that switches based on the switching operation of the operator, the cost can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a hydraulic excavator. FIG. 2 is a hydraulic control circuit diagram for the alignment. Fig. 3 (A) is a plan view of the first and second switching valves, and (B) is a bottom view of the first and second switching valves. Fig. 4 (A) is a front view of the first and second switching valves, and (B) is a side view of the first and second switching valves. FIG. 5 (A) is an enlarged cross-sectional view of XX of FIG. 3 (A), and FIG. 5 (B) is an enlarged cross-sectional view of YY of FIG. 3 (B). FIG. 6 is a diagram showing classifications of entertainment and switching positions of the first and second switching valves. FIG. 7 is a hydraulic control circuit diagram for an attachment showing an example. FIGS. 8 (A) and 8 (B) are plan views of the switching valve in the ^ * example, and FIG. 9 is a front view in cross section. FIG. 9 is a plan view showing the arrangement of the switching element and the first to fourth switching valves. FIG. 5 is a diagram showing a switching position of the switch.

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment 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 The boom 4 is supported so as to be able to swing up and down, a stick 5 is supported at the tip of the boom 4 so as to swing back and forth, and a bucket 6 attached to the tip of the stick 5 is provided. In addition, various hydraulic actuators such as a left and right traveling motor (not shown), a swing motor (not shown), a boom cylinder 7, a stick cylinder 8, and a bucket cylinder 9 are provided. In addition, depending on the work performed by the hydraulic excavator 1, various attachments 10 that are operated by hydraulic pressure such as breakers and ruptures can be mounted, and the hydraulic control for the hydraulic control 10 can be performed. The present invention has been described. Here, in the present embodiment, the I3 arrangement 10 is classified into four as shown in FIG. 6, so that different hydraulic control can be performed for each classification. Toes The attachment 10 of the first category is a double-acting type which is sufficient for the flow rate of the main pump, which will be described later, and in which oil flows in both directions, and corresponds to, for example, a small crusher. In addition, the second actuator 10 is a single-acting type in which the flow rate of the main pump is sufficient and the oil flows only in one direction, such as a small breaker. Further, the attachment 10 of the third category requires a flow rate of two main pumps and is a double-acting type in which oil flows in both directions. Furthermore, the fourth ^! The attachment 10 requires a flow rate of two main pumps and is a single-acting type in which pressure oil flows only in one direction. For example, a large breaker or the like is applicable. Now, FIG. 2 shows a hydraulic control circuit diagram of the attachment 10. In FIG. 2, 11, 12 are the first and second main pumps, 13 is the pilot pump, 14 is the oil tank, Reference numeral 15 denotes a control valve unit. The control valve unit 15 includes a control valve 16 for an attachment which controls the supply and discharge of pressure oil to the attachment 10 and a control valve 16 for the hydraulic actuating unit of the above-mentioned type. Control knobs 17 to 23 for controlling hydraulic oil supply and discharge, control knobs for second center bypass 24, described later, relief valves 25 and 26 for first and second negative controls, line relief Various knobs such as valves (not shown) are incorporated. In Fig. 2, ① and ①, ② and ②, ③ and ③, ④ and それ are connected. Briefly describing the main oil passages formed in the control valve unit 15, A is the first sensor bypass passage, B is the second sensor bypass passage, and The centrifugal bypass oil passage A controls the pressure oil from the first main pump 11 and controls the central lubrication passages 17 a, 17 a, 16, 18, 19, and 20. This is an oil line that flows to the first negative control port, Reno ^ Rev 25, via 16a, 18a, 19a, 20a, and the second oil bypass line B is the second main line. The pressure oil from the pump 12 is passed through the center bypass valve passages 21a, 22a, 23a and 24a formed in the control valves 21 22 23 24. This is an oil passage for the negative control valve 26. C is the first parallel oil passage, D is the second parallel oil passage, and the first parallel oil passage C is the control valves 17, 16, 18 that control the hydraulic oil from the first main pump 11. To supply 1,9,20 The second parallel oil passage D is an oil passage for supplying pressurized oil from the second main pump 12 to the control valves 21, 22, 23, and 24. Further, E is a tank oil passage, and the tank oil passage E is used to supply oil from the control valves 16 to 23 and the first and second negative control valves V 25 and 26. This is an oil passage for flowing into tank 14. Here, the pressure of the first and second center bypass oil passages B supplied to the BB-second negative control valves 25 and 26 is a negative control signal pressure as the first and second negative control lines F and G. And then from the first and second negative control lines F and G to the flow rate variable means 27 of the first and second main pumps 11 and 12. The flow rate varying means 27 reduces the pump discharge amount when the negative control signal pressure is high, and increases the pump discharge amount when the negative control signal pressure is low. It is configured to perform the flow control of 11 and 12. In addition, the control valve 16 for attachment is a three-position switching valve having first and second pilot ports 16b and 16c, and is connected to both pilot ports 16b and 16c. In the state where the throttle pressure is not input, the hydraulic oil in the first oil bypass oil passage A flows downstream through the oil bypass valve line 16a, while the hydraulic oil is supplied to and discharged from the oil pump 10. Although it is located at the neutral position N where control is not performed, the pilot bypass pressure is input to the first pilot port 16b, thereby closing the center bypass valve line 16a and the pressure of the supply oil line H described later. It switches to the first pressure oil supply position X where oil is supplied to the first oil passage J and the oil in the second oil passage K is discharged to the oil passage E. When pilot pressure is supplied to port 16c, the center While closing the bypass valve line 16a, supply the pressure oil in the supply oil passage H to the second attachment oil passage K, and discharge the oil in the first attachment oil passage J to the tank oil passage E. It is configured to switch to the second pressure oil supply position Y.

■ 3 The supply oil passage H is an oil passage for supplying the pressure oil of the first parallel oil passage C to the attachment control valve 16 via the valve 28 (the oil passage is the first pump of the present invention). The hydraulic oil of the second main pump 12 is supplied to the second pump oil passage opening / closing valves 35 and 35 described later. The second oil passage L and the second oil passage L for supplying to the control valve 16 via the valve 29 are connected to the control valve 16 for the equipment. The first and second attachment oil passages K are oil passages connected to the attachment 10, but the attachment 10 is a double-acting attachment, that is, the first and third classifications described above. One of the oils of the first arrangement 10 is connected to one oil of the double-acting arrangement 10, an oil passage J for the first arrangement is connected to the outlet 10 a, and the other oil ¾λ The second oil passage Κ is connected to the outlet 1 Ob. The attachment 10 is a single-acting attachment, that is, the second and fourth ^! For the oil pump 10: ^, the oil inlet 10 a of the single-acting oil tank 10 is connected to the oil passage J for the first oil pump, and the oil outlet J is connected to the oil outlet 10 b. The oil passage K for the second anchorage is connected. Further, the control valve for the Bito-Nicenta bypass (corresponding to the flow control valve of the second pump of the present invention) 24 is a third-position fi¾ which has first and second pilot ports 24 b and 24 c. [If the pilot port pressure is not input to both pilot ports 24b and 24c because of a valve change, the center bypass valve line 24a is opened to open the second centrifugal bypass oil passage B Although it is located at the neutral position N where the hydraulic oil flows downstream, the pilot pressure is supplied to the first pipeline port 24 to close the valve passage 24 a for the above-mentioned pipeline. It is configured to switch to X. The control valve 21, 22, 23, through which the second bypass oil passage B passes, the first and second bypass valve passages 21 a, 22 a, 23 a are open, and the second When the evening bypass control valve 24 is located at the neutral position N where the sensing bypass valve path 24 a is opened, it is guided to the flow rate variable means 27 via the second negative control line G described above. The negative control signal pressure increases, and the second main pump 12 is controlled so that the pump discharge rate decreases. In addition, when the second control valve for second bypass 24 is located at the closed position X, the negative control signal pressure decreases, and the second main pump 12 increases the pump discharge amount. Is controlled as follows. The control valve 24 for the second sensor bypass is used to control the supply of pressure oil to other hydraulic actuators when the pilot pressure is supplied to the second pilot port 24c. The position is switched to the supply position Y, but this control is omitted. On the other hand, reference numeral 30 designates a pit opening and a rev. The pilot rev 30 is an attachment pedal (corresponding to the attachment operating tool of the present invention, but is not limited to the pedal but may be a lever operated by hand. 3) First, second, and third output ports 30a, 30b, and 30c that output the pilot pressure based on only the operation of 31 . In other words, the pedal 31 for the actuator is operated only in the forward direction when the attachment 10 is a single-acting type: ^, and is depressed in both directions when the T is a double-acting type. wm One output port 30a is connected to the first pilot port 1 6b of the armor foot base lever 16 based on the fact that the operation pedal 31 has been depressed forward. The second output port 3 Ob outputs pilot pressure to the second pilot port 16c of the attachment control valve 16 based on the depression of the attachment pedal 31 rearward. The third output port 30c outputs the pipe pressure to the second pump control oil passage M, which will be described later, regardless of whether the attachment pedal 31 is tipped forward or backward. It is configured as follows. Here, the oil passage M for controlling the pump is connected to the pilot port pressure output from the third output port 30 c of the pilot valve 30 via the first switching valve 33 described later. 3 Pilot port oil passage for supplying to the first pilot port 24b of the second control valve 24 for the secondary pump and the pilot port 35a of the second pump oil passage opening / closing valve 35. N is a single-acting pilot oil passage, and the single-acting pilot oil passage N transmits pilot pressure output from the pilot pump 13 through a second switching valve 34 described later. This is an oil passage for supplying to the pilot port 36 a of the relief oil passage on-off valve 36 and the pilot port 37 a of the discharge oil passage on-off valve 37. As shown in FIGS. 3 to 5, the first and second switching valves 33, 34 are spool-type, three-port, two-way switching valves that are threaded in one valve body 38. The switching valve 33 includes an input port 33 a connected to the third output port 30 c of the nozzle port valve 30, a tank port 33 b connected to the oil tank 14, and a second It has a first pilot port 24 b of the center bypass control valve 24 and an output port 33 c connected to the pie port 35 a of the second pump oil passage opening / closing valve 35. The first switching valve 33 closes the input port 33a when the operator switches the lever 33d. And the closed position X where the valve path from the output port 33 c to the tank port 33 b is to be closed, and the evening port 33 b is closed, and the input port 33 a to the output port 33 c It is configured to switch to the open position Y where the valve path opens. Thus, when the first switching valve 33 is in the closed position X, the first pilot port 24 of the second center bypass control valve 24 and the pilot port 35 of the second pump oil closing valve 35 are provided. Is connected to the oil tank 14, but when the first switching valve 33 is in the open position Y, the third output port 3 of the pierce pulp 30 is operated based on the operation of the attachment pedal 31. The pilot port pressure output from 0c is applied to the first pilot port 24b of the control valve 24, and the pilot port 35 of the second pump oil passage open / close valve 35. To be supplied. Also, the second switching valve 34 includes a pump port 34 a connected to the W lot pump 13, a tank port 34 b connected to the oil tank 14, and a relief oil passage opening / closing valve 36. It has a pilot port 36a and an output port 34c connected to the pilot port 37a of the discharge oil passage opening / closing valve 37. When the operator switches the reno-34 d, the input port 34 a is closed, and the closing position X where a valve path from the output port 34 c to the tank port 34 b is planned. It is configured to switch to an open position Y in which the port 34b is closed and the valve path from the input port 34a to the output port 34c is open. Thus, when the second switching valve 34 is in the closed position X, the pilot port 36 a of the relief oil passage on-off valve 36 and the pilot port 37 a of the discharge oil passage on-off valve 37 are connected to the oil tank 14. When the second switching valve 34 is in the open position Y, the pilot pressure output from the pilot pump 13 is applied to the pilot port 36 a of the relief oil passage opening / closing valve 36 and the discharge oil. The air is supplied to the pilot port 37 a of the road on-off valve 37. Further, the second pump oil passage opening / closing valve 35 is arranged in the second pump oil passage L from the second main pump 12 to the attachment control valve 16 as described above. The on-off valve 35 is a two-way reversing valve having a pilot port 35a, and closes the second pump oil line L when the pilot port pressure is not input to the pilot port 35a. It is located at position X, but there is no pipe pressure at W port 35 a. It is configured to be switched to an open position Y for opening the second pump oil passage L when input. And, when the second pump oil passage opening / closing valve 35 is located at the closed position X, the pressure oil from the second main pump 12 is supplied to the! ^ The supply oil is not supplied to the passage H, and only the pressure oil from the first main pump 11 is supplied to the supply oil passage H via the second parallel oil passage C. ing. On the other hand, when the second pump oil passage opening / closing valve 35 is at the open position Y, the pressure oil from the second main pump 12 is supplied via the second pump oil passage L! The supply oil is supplied to the free passage H, so that the pressure oil of the first and second main pumps 11 and 12 is supplied to the supply oil passage H. On the other hand, P is a discharge oil passage that branches off from the oil passage K for the tirl second arrangement and reaches the oil tank 14, and a leak discharge oil passage opening / closing valve 37 is arranged in the discharge oil passage P. It is established. This discharge oil passage opening / closing valve 37 is a pilot operated M: valve, and when the pilot pressure is not input to the pilot port 37a, the oil from the second attachment oil passage K to the oil tank 14 is supplied. The flow is blocked, but the flow in the reverse direction is allowed, but it is in a one-way state. However, when the pilot pressure is input to the outlet port 37a, the oil passage for the second alignment is used. It is configured to be in a bidirectional state that allows the flow of oil from K to the oil tank 14 and the flow in the opposite direction. The exhaust oil passage opening / closing valve 37 is equipped with a single-acting attachment 10 as will be described later: it is excellent in the back pressure of ^, but instead of the oil passage opening / closing valve 37, An on-off valve similar to the second pump oil passage on-off valve 35 described above and a relief oil passage on-off valve 36 described later can also be used. Q is a relief oil passage, and the relief oil passage Q branches off from the knitting first attachment oil passage J and merges into the second equipment oil passage K, and the second oil passage K It is formed so as to reach the oil tank 14 from the oil passage K via the self-discharging oil passage P. In this relief oil passage Q, the pressure of the first attachment oil passage K is set in advance. When the pressure exceeds the set pressure (the set pressure is set to limit the maximum BE force acting on a single-acting attachment, for example, a breaker), the oil in the oil passage J for the first attachment is discharged. A relief valve 39 for flowing into the oil tank 14 and a relief oil passage opening / closing valve 36 are provided. The tulB relief oil passage opening / closing valve 36 is a two-way reversing valve provided with a pilot port 36a. When the pilot port pressure is not input to the pilot port 36a, the relief valve is opened. Although it is located at the closed position X where the oil passage Q is closed, it is configured to switch to the open position Y where the relief oil passage Q is opened by inputting the pipe outlet pressure to the outlet port 36a. Have been. Now, as described above, the first and second switching valves 33, 34 are of a manual type that are switched by an operator's operation, as described above. The hydraulic control for the attachment 10 can be changed based on the switching operation of 34. In the following description, it is assumed that the attachment 10 is operated independently and no other hydraulic actuating-evening operation is performed. First, when the first switching valve 33 is located at the closed position X, as described above, the first pilot port 24 b of the second control bypass pulp 24 b and the second pump oil The pilot port 35 a of the closed valve 35 is in communication with the oil tank 14, and the control valve 24 for the second sensor bypass is located at the neutral position N, and the second pump oil passage The on-off valve 35 is located in the closed position X. As a result, only the pressurized oil from the first main pump 11 is supplied to the supply oil passage H that supplies the pressurized oil to the control norb 16 for attachment, and the second main pump 12 Is controlled to decrease. On the other hand, in a state where the first switching valve 33 is located at the open position Y, when the attachment head 31 is operated, the third output port 30 c of the pilot valve 30 is connected to the second pump control oil passage. The pilot pressure output to M is applied to the first pilot port 24 b of the second center bypass control valve 24 and the pilot port 3 of the second pump oil passage opening / closing valve 35.

The second control valve 24 is switched to the closed position X, and the second pump oil passage opening / closing valve 35 is switched to the open position Y. As a result, the first and second main pumps 11 and 12 are connected to the supply oil passage H for supplying pressure oil to the attachment control valve 16.

The second main pump 12 is controlled so as to increase the pump discharge amount while the pressure oil from 12 is supplied. In addition, when the second switching valve 34 is in the closed position X, as described above, the pilot port 36a of the relief oil passage opening / closing valve 36 and the piping of the discharge oil passage opening / closing valve 37, as described above. The outlet port 37 a is in communication with the oil tank 14, so that the relief oil passage opening / closing valve 36 is located at the closed position X, and the discharge oil passage closing valve 37 is in a one-way state. Accordingly, oil discharge from the first and second alignment oil passages K to the oil tank 14 via the relief oil passage 0 and the discharge oil passage P is prevented. In this state, if the operation pedal 31 for the attachment is depressed forward or backward to operate the double-acting attachment 10, the first or second output port 30a, 3 of the pilot valve 30 is operated. 0 The control knob 16 for attachment is switched to the first or second hydraulic oil supply position X, Y by the pilot pressure output from b, and the hydraulic oil in the supply oil passage H is used for the first or second attachment. Supplied to oilway << 1, The hydraulic oil supplied to the first or second attachment oil passage K is supplied to one of the oil outflow ports 10 a or 10 Ob of the attachment 10, while the other oil outflow port 10 is supplied to the other oil outflow port 10. The oil discharged from b or 10a passes through the second or first attachment oil passage, J, to the attachment control valve 16 and then from the attachment control valve 16 to the tank. The oil is discharged to oil tank 14 via oil passage E. On the other hand, when the second switching valve 34 is located at the open position Y, as described above, the pilot pressure from the pilot pump 13 causes the pilot port 36 a of the relief oil passage opening / closing valve 36 and the pilot port 36 a and The oil is supplied to the pilot port 37 a of the discharge oil passage opening / closing valve 37, whereby the relief oil passage closing valve 36 is located at the open position Y, and the discharge oil passage opening / closing valve 37 is in a two-way state. In this state, when the operation pedal 31 for operating the single operation type actuator 10 is depressed forward, the output is output from the first output port 30a of the pilot valve 30. The control knob 16 for attachment is switched to the first pressure oil supply position Y by the pipe port pressure, and the pressure oil in the supply oil passage H is supplied to the first attachment oil passage J. The pressurized oil supplied to the first attachment oil passage J is supplied to the oil port 10a of the attachment 10 while the second oil is supplied from the oil outlet 10b. The oil discharged to the oil passage K for the fluid flows from the oil passage P to the oil tank 14 via the discharge oil passage opening / closing valve 37 in the two-way state, and is thus a single-acting type.ァ 10, for example, the back pressure acting on the playing power can be increased. In addition, since the relief oil passage Q is opened by the relief oil passage opening / closing valve 36 at the opening position Y, the pressure of the hydraulic oil in the oil passage J is set to the relief valve 39. When the pressure exceeds the pressure, the pressurized oil is discharged to the oil tank 14 via the relief oil passage, the second attachment oil passage, and the discharge oil passage P, and the maximum pressure supplied to the attachment 10 is reduced. The pressure can be limited to the set pressure of the relief valve 39. When the various excavators 10 are mounted on the excavator 1, the first switching valve 33 is located at the closed position X in the first type of excavator 10. At the same time, by positioning the second switching valve 34 in the closed position X, only the pressurized oil from the first main pump 11 is supplied to the attachment 10, and the pressurized oil is supplied in both directions. A hydraulic control circuit for the expression unit is formed. In the case of the attachment 10 of the second category, the attachment 10 is achieved by positioning the first switching valve 33 at the closed position X and the second switching valve 34 at the open position Y. A hydraulic control circuit for a single-acting arrangement capable of supplying only the pressure oil from the first main pump 11 and operating the relief and reducing the back pressure is formed. You. Further, in the third class of attachments 10; ^, the first switching valve 33 is located at the open position Y and the second switching valve 34 is located at the closed position X, so that A hydraulic control circuit for a double-acting attachment that supplies hydraulic oil from the first and second main pumps 11 and 12 and supplies hydraulic oil in both directions is formed. Furthermore, in the case of the attachment 10 of the fourth category, the attachment 10 is made by positioning the first switching valve 33 at the open position Y and the second switching valve 34 at the open position Y. A single-acting gear pump that can supply hydraulic oil from the first and second main pumps 11 and 12 and can operate the relief and reduce the back pressure Hydraulic control circuit for the vehicle is formed. As a result, the change of the hydraulic control circuit corresponding to the instruments 10 of the four categories I & I can be performed by switching the first and second two manual switching valves 33, 34. As a result, the circuit can be easily changed when the attachment 10 is replaced, and the occurrence of a mistake during the switching operation can be suppressed. Further, the first and second switching valves 33, 34 are As described above, since it is a spool type, there is an advantage that cost can be reduced as compared with the ball valve used. Note that the present invention is not limited to the above-described embodiment of course, and in the above-described embodiment, the first and second switching valves 33 and 34 are of a manual type. The switching valves 33, 34 may be configured by, for example, electromagnetic valves that are switched based on the operation of a selector switch disposed in a driver's seat. In addition, even if the attachment is sufficient for the flow rate of one pump, the flow rate of the first pump alone is sufficient, for example, during the combined operation of the hydraulic actuator and other attachments supplied with pressure oil from the first pump. If not, it is a matter of course that the second pump can be configured to supply pressure oil to the attachment.

Industrial applicability

The present invention relates to a case in which a hydraulic control circuit is changed to accommodate various types of attachments with different hydraulic controls, such as attachments with different required flow rates and single-acting and double-acting attachments, when mounting the attachment. Widely applicable.

Claims

The scope of the claims

1. A hydraulically operated element, an attachment control valve for controlling the supply and discharge of pressure oil to the element, a first and a second pump, and a hydraulic oil from the first pump. A hydraulic control circuit for an attachment including a first pump oil passage for supplying to a control valve for the atticument, wherein the hydraulic control circuit for the attachment includes a control valve for the ifts actuator, which is configured to supply the hydraulic oil from the second pump to the hydraulic control circuit for the attachment. When providing a second pump oil passage for supplying oil to the second pump oil passage and a second pump oil passage for controlling the flow rate of the second pump, both the second pump oil passage and the second pump oil passage are provided. A hydraulic control circuit for attachment in Εΐδ shelf control, wherein the oil passage is opened and closed based on the switching operation of one switching means.

2. A hydraulically actuated actuator, an actuator control valve for controlling the supply and discharge of pressurized oil to the actuator, a control valve for the actuator, and a control oil for the actuator. ^ An oil hydraulic control circuit for an attachment provided with first and second oil passages for connection to the λ outlet, wherein oil in the oil passage for first attachment is supplied to the oil pressure control circuit for oil attachment. In providing a relief oil passage that flows to the tank side via a relief valve and a discharge oil passage that allows oil for the second attachment oil passage to flow to the tank side, opening and closing of both the relief oil passage and the discharge oil passage And a hydraulic control circuit for alignment in a building, wherein the hydraulic pressure control circuit for construction is configured to be able to perform the operation based on a switching operation of one switching means.

3. A hydraulically operated attachment, an attachment control valve for controlling the supply and discharge of pressurized oil to and from the attachment, and a control valve for the attachment and the 3 oil outlet of the attachment. First and second attachment oil passages to be connected, first and second pumps, and a first pump oil passage for supplying pressure oil from the first pump to the attachment control valve. A hydraulic control circuit for attachment, a hydraulic control circuit for attachment, a second pump oil passage for supplying pressure oil from a second pump to the control valve for attachment, and a flow rate of the second pump. The oil from the second pump control oil passage for control and the oil from the first arrangement oil passage to the tank side via a relief valve. In providing the relief oil passage for flowing and the discharge oil passage for flowing the oil of the second attachment oil passage to the tank side, the knitting second pump oil passage and the second pump control based on the switching operation of the first switching means The opening and closing of both oil passages of the oil passage for use, and the opening and closing of both oil passages of the relief oil passage and the discharge oil passage based on the switching operation of the second switching means. Hydraulic control circuit for equipment

4. In claim 1 or 3, the second oil passage for pump control is a pilot oil for supplying a pipe outlet pressure to a flow control knob of the second pump based on an operation of the operation device for alignment. The second pump oil passage is opened and closed by a second pump oil passage opening / closing valve that is operated by pilot pressure supplied to the second pump control oil passage. The switching means for opening and closing both the oil passage and the second pump control oil passage is a switching valve for opening and closing the second pump control oil passage. Hydraulic control circuit.

5. In claim 2 or 3, the relief oil passage is opened and closed by a relief oil passage opening / closing valve operated by pilot pressure, and the discharge oil passage is opened and closed by a discharge oil passage operated by pilot pressure. The switching means for opening and closing both the relief oil passage and the discharge oil passage is a switching valve that supplies pilot pressure to the three on-off valves! A hydraulic control circuit for alignment in a building command.

6. An apparatus according to claim 1, 2, 3, 4 or 5, wherein the switching means is a manual spool valve which is switched based on a switching operation by an operator. Hydraulic control circuit for evening chips.