JP2004076411A - Hydraulic circuit device for hydraulic excavator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce mandays on an assembly in installation of a hydraulic breaker irrespective of the magnitude of the allowable pressure of the installed hydraulic breaker, in a hydraulic circuit device with a hydraulic circuit for a front attachment, to which the hydraulic breaker can be installed. <P>SOLUTION: A variable relief valve 63 is mounted on an actuator-side circuit section for the hydraulic circuit for the front attachment, and the set pressure is made changeable at the two stages of low pressure and high pressure by operating pilot hydraulic pressure by a set-pressure changing device 64. The variable relief valve 63 is installed to a mounting port for an overload relief valve set up to a valve housing for a control valve deice 5, the setting of its low pressure is equalized to the allowable pressure of the hydraulic breaker having low-pressure specifications and the setting of the high pressure is equalized to the setting of the overflow relief valve for the normal front attachment. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydraulic circuit device of a hydraulic shovel, and more particularly to a hydraulic circuit device of a hydraulic shovel having a hydraulic circuit for a front attachment to which a hydraulic breaker, which is a front attachment of the hydraulic shovel, can be mounted.
[0002]
[Prior art]
Hydraulic excavators are used not only for excavation work with buckets but also for work with hydraulic breakers and crushers, etc.Therefore, the hydraulic circuit devices of hydraulic shovels are specially designed so that front attachments such as hydraulic breakers and crushers can be attached. A hydraulic circuit (a hydraulic circuit for a front attachment) is provided. This hydraulic circuit is constituted by a spare directional control valve in the control valve device. When the hydraulic breaker is installed, the hydraulic circuit breaker is mounted on the high-pressure side actuator circuit portion in which pressure oil is supplied from the directional control valve to the hydraulic breaker. The low-pressure side actuator circuit portion from which the pressure oil that has worked in the above is discharged is provided with a high-pressure accumulator and a low-pressure accumulator for absorbing the pulsation of the hydraulic pressure at the time of driving the hydraulic breaker.
[0003]
Further, as a hydraulic circuit device of a hydraulic shovel, there is a hydraulic circuit device having a front attachment hydraulic circuit capable of replacing and mounting a hydraulic breaker and a crusher, as described in Japanese Patent No. 322268, for example. This makes it possible to switch to a circuit configuration that is suitable for each of the hydraulic breaker and the crusher.When the hydraulic breaker is installed, the circuit configuration returns the pressure oil on the discharge side directly to the tank via the filter. When switching and mounting the crusher, the circuit configuration is changed to a circuit configuration capable of supplying pressure oil from any side to the hydraulic cylinder for the crusher.
[0004]
Further, a hydraulic circuit device of a hydraulic shovel is generally provided with a main relief valve and an overload relief valve for protecting the hydraulic circuit and the actuator from excessive pressure. The main relief valve is provided in the circuit part on the pump side in the control valve device, and protects the entire hydraulic circuit from excessive pressure by limiting the maximum discharge pressure of the hydraulic pump. The overload relief valve is provided in an oil passage on the actuator port side of the directional control valve in the control valve device, and prevents a temporary overload of the actuator. Usually, the relief pressure of the overload relief valve is set higher than the relief pressure of the main relief valve.
[0005]
[Problems to be solved by the invention]
The allowable pressure of a hydraulic breaker, which is a front attachment of a hydraulic excavator, differs depending on the manufacturer. There is no problem if the allowable pressure of the hydraulic breaker to be mounted is higher than the relief pressure of the main relief valve. However, when the allowable pressure of the hydraulic breaker is lower than the relief pressure of the main relief valve, excessive pressure is applied to the hydraulic breaker by the hydraulic oil from the hydraulic pump, which causes a failure of the hydraulic breaker. Therefore, when installing a hydraulic breaker whose allowable pressure is lower than the relief pressure of the main relief valve, a relief valve for a low-pressure breaker in which the relief pressure is set low in the high-pressure side actuator circuit of the front attachment hydraulic circuit separately from the main relief valve The relief valve protects the hydraulic breaker from excessive pressure. In many cases, the relief valve for the low-pressure breaker is not provided in the standard hydraulic circuit for the front attachment, so the installation of such a relief valve is usually done by modifying the hydraulic circuit for the standard front attachment . A relief valve for a low-pressure breaker is usually installed on a hydraulic source side pipe on a boom of a hydraulic excavator.
[0006]
Once the front attachment hydraulic circuit has been modified to incorporate a low-pressure breaker relief valve and then replaced with a higher allowable pressure hydraulic breaker, remove the low-pressure breaker relief valve or stop before and after the relief valve. It is necessary to provide a valve and close the stop valve.
[0007]
In a hydraulic circuit device having a front-attachment hydraulic circuit capable of replacing and installing a hydraulic breaker and a crusher, the same applies when a hydraulic breaker having a low allowable pressure is mounted or thereafter replaced with a hydraulic breaker having a high allowable pressure. When installing a hydraulic breaker with a low allowable pressure, it is necessary to provide a relief valve for the low pressure breaker.When replacing the hydraulic breaker with a high allowable pressure, remove the relief valve for the low pressure breaker It is necessary to provide a stop valve before and after and to close the stop valve. Furthermore, after installing a relief valve for the low pressure breaker and corresponding to a hydraulic breaker with a low allowable pressure, when installing the crusher, remove the relief valve for the low pressure breaker in the same way, or in the circuit part before and after the relief valve It is necessary to provide a stop valve and to close the stop valve. Further, in this case, since a high-pressure accumulator is unnecessary, a stop valve must be provided at the inlet of the high-pressure accumulator, and an operation of closing the stop valve is also required.
[0008]
As described above, in the prior art, depending on the allowable pressure of the hydraulic breaker to be mounted, it is necessary to install a relief valve for the low-pressure breaker in the high-pressure actuator circuit portion (the hydraulic-source-side piping on the boom). And increase the amount of work. Further, in a hydraulic circuit device capable of replacing and mounting a hydraulic breaker and a crusher, a stop valve is opened / closed when the hydraulic breaker and the crusher are replaced, thereby increasing the time required for replacement.
[0009]
A first object of the present invention is to provide a hydraulic circuit device having a hydraulic circuit for a front attachment to which a hydraulic breaker, which is a front attachment of a hydraulic shovel, can be mounted, regardless of the allowable pressure of the hydraulic breaker to be mounted. An object of the present invention is to provide a hydraulic circuit device of a hydraulic shovel, which can reduce the number of assembling steps at the time and reduce the amount of work.
[0010]
A second object of the present invention is to reduce the work time required for replacing a hydraulic breaker with a crusher in a hydraulic circuit device having a hydraulic circuit for a front attachment that can be replaced and mounted with a hydraulic breaker and a crusher. It is an object of the present invention to provide a hydraulic circuit device of a hydraulic shovel that can be used.
[0011]
[Means for Solving the Problems]
(1) In order to achieve the first object, the present invention includes at least one hydraulic pump, a main relief valve for regulating a maximum discharge pressure of the hydraulic pump, and a directional control valve for a front attachment. A hydraulic circuit device for a hydraulic shovel having a hydraulic circuit for a front attachment and capable of mounting a hydraulic breaker which is a front attachment of the hydraulic shovel, wherein when the hydraulic breaker is mounted, the hydraulic pressure is transmitted from a direction control valve of the hydraulic circuit for the front attachment to the hydraulic pressure. A variable relief valve provided in a high-pressure side actuator circuit portion for supplying pressure oil to the breaker; and a set pressure changing means for switching a set pressure of the variable relief valve to at least two stages of a low pressure and a high pressure. Setting the low pressure of the variable relief valve to be lower than the relief pressure of the main relief valve. Comb, it is assumed that the setting of the pressure was higher than the relief pressure of the main relief valve.
[0012]
With such a configuration, when the allowable pressure of the mounted hydraulic breaker is lower than the relief pressure of the main relief valve, the set pressure of the variable relief valve is switched to low pressure by the set pressure changing means, so that the hydraulic breaker is controlled by the variable relief valve. It can protect against excessive pressure. If the allowable pressure of the mounted hydraulic breaker is higher than the relief pressure of the main relief valve, the set pressure of the variable relief valve is switched to a high pressure by the set pressure changing means, so that the hydraulic relief breaker is operated by the main relief valve. Can be protected.
[0013]
By simply operating the set pressure changing means, the set pressure of the variable relief valve is switched, and the function is equivalent to the presence or absence of the conventional low pressure relief valve.Therefore, it is necessary to install and remove the low pressure relief valve. In addition, regardless of the allowable pressure of the hydraulic breaker to be mounted, it is possible to greatly reduce the number of assembly steps and the amount of work when mounting the hydraulic breaker.
[0014]
Also, depending on the allowable pressure of the hydraulic breaker, conventionally two types of hydraulic circuits had to be used, and accordingly there were two types of piping components. However, in the present invention, there is no need to change the hydraulic circuit. Piping components can be unified into one type, and component management becomes easy.
[0015]
(2) In order to achieve the second object, the present invention provides at least one hydraulic pump, a main relief valve for regulating a maximum discharge pressure of the hydraulic pump, and a directional control valve for a front attachment. A hydraulic circuit for a hydraulic excavator having a hydraulic circuit for a front attachment having a hydraulic circuit breaker, which is a front attachment of a hydraulic shovel, and capable of replacing a hydraulic breaker with a crusher. And a variable relief valve provided in a high-pressure side actuator circuit portion in which pressure oil is supplied from the direction control valve of the front attachment hydraulic circuit to the hydraulic breaker, and the set pressure of the variable relief valve is at least a low pressure and a high pressure. And a set pressure changing means for switching the pressure to two stages. Of the low pressure set lower than the relief pressure of the main relief valve, it is assumed that the setting of the pressure was higher than the relief pressure of the main relief valve.
[0016]
Thus, when the hydraulic breaker is mounted, it is possible to significantly reduce the number of assembling steps and the amount of work regardless of the allowable pressure of the hydraulic breaker to be mounted as described in (1) above.
[0017]
In addition, when replacing the hydraulic breaker with a low allowable pressure with a crusher, the set pressure of the variable relief valve is switched to high pressure by the set pressure changing means, so that the hydraulic cylinder of the crusher is reduced from excessive pressure by the main relief valve. Can be protected.
[0018]
By simply operating the setting pressure changing means, the setting pressure of the variable relief valve is switched, and it has the same function as the presence or absence of the conventional low pressure relief valve, so installation of the low pressure relief valve and opening and closing of the stop valve The work time required for exchanging the hydraulic breaker with the crusher can be greatly reduced without the need for a crusher.
[0019]
(3) In the above (1) or (2), preferably, the variable relief valve is provided at a mounting port of an overload relief valve provided in a valve housing of a control valve device including the directional control valve for the front attachment. It is installed in place of the overload relief valve, and the setting of the high pressure of the variable relief valve is the same as the relief pressure of the overload relief valve.
[0020]
Thereby, the variable relief valve also functions as a conventional overload relief valve, and the number of parts can be reduced. Further, since the variable relief valve is installed at the existing mounting port, there is no need to change the valve housing of the control valve device 5.
[0021]
(4) In the above (1) or (2), preferably, the variable relief valve can change a relief set pressure by operating a pilot oil pressure, and the set pressure changing means turns on the pilot oil pressure, The variable relief valve is set to a low pressure when the pilot hydraulic pressure is off, and is set to a high pressure when the pilot hydraulic pressure is on.
[0022]
Thus, the variable relief valve can easily change the set pressure by turning on and off the pilot hydraulic pressure.
[0023]
(5) In the above (4), preferably, the set pressure changing means has a changeover switch and a solenoid valve, and the changeover switch is installed in a cab of a hydraulic shovel, and the solenoid valve is switched by switching the changeover switch. To turn on and off the pilot hydraulic pressure.
[0024]
Thus, the set pressure of the variable relief valve can be easily changed when the hydraulic breaker is mounted or when the hydraulic breaker and the crusher are replaced and mounted simply by operating the changeover switch in the cab.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0026]
FIG. 1 is an overall configuration diagram of a hydraulic circuit device of a hydraulic shovel according to a first embodiment of the present invention. In FIG. 1, a hydraulic circuit device according to the present embodiment is connected to first and second two hydraulic pumps 1 and 2 and discharge oil passages 3 and 4 of the first and second hydraulic pumps 1 and 2. A control valve device 5, a plurality of hydraulic actuators 6 to 11 connected to the control valve device 5, and a hydraulic breaker 12.
[0027]
The control valve device 5 includes a first valve section 15 including a center bypass type directional control valve 21 to 24 and a second valve section 16 including a center bypass type directional control valve 25 to 29. The directional control valves 21 to 24 are connected in the illustrated order on a center bypass line 31 connected to the discharge oil passage 3 of the first hydraulic pump 1, and the directional control valves 25 to 29 of the second valve section 16 are connected to the second hydraulic pump It is connected in the illustrated order on a center bypass line 32 connected to the second discharge oil passage 4. In the first valve section 15, the most upstream portions of the center bypass lines 31, 32 are connected via check valves 36, 37 to a main relief valve 35 that regulates the maximum discharge pressure of the first and second hydraulic pumps 1, 2. ing.
[0028]
The hydraulic actuator 6 is a right traveling motor, the hydraulic actuator 7 is a bucket cylinder, the hydraulic actuator 8 is a boom cylinder, the hydraulic actuator 9 is a turning motor, the hydraulic actuator 10 is an arm cylinder, the hydraulic actuator 11 is a left traveling motor, and a direction control valve 21. Is for right running, the directional control valve 22 is for the bucket, the directional control valve 23 is for the first boom, the directional control valve 24 is for the second arm, the directional control valve 25 is for turning, and the directional control valve 26 is for the first arm. The direction control valve 27 is for the second boom, the direction control valve 28 is for standby (for hydraulic breaker), and the direction control valve 29 is for left running. The oil passages on the actuator port side of the directional control valves 21 to 24 and 25 to 29 are connected to the respective hydraulic actuators 6 to 11 and the hydraulic breaker 12, and the first and second hydraulic pressures are controlled by the directional control valves 21 to 24 and 25 to 29. The flow of the pressure oil supplied from the pumps 1 and 2 to the hydraulic actuators 6 to 11 and the hydraulic breaker 12 is controlled.
[0029]
In the first valve section 15, bucket overload relief valve units 41 and 42 are provided in an oil passage on the actuator port side of the bucket directional control valve 22, and the actuator port of the boom directional control valves 23 and 27 is provided. The boom overload relief valve units 43 and 44 are provided in the oil passage on the side. In the second valve section 16, the oil passage on the actuator port side of the spare directional control valve 28 is provided with a spare overload relief valve. Units 45 and 46 are provided.
[0030]
The spare directional control valve 28, the main relief valve 35, and the overload relief valve units 45 and 46 of the control valve device 5 constitute a hydraulic circuit for front attachment together with the second hydraulic pump 2 and an actuator circuit described later.
[0031]
FIG. 2 shows details of the hydraulic circuit for the front attachment. This drawing shows only a portion related to the hydraulic circuit for front attachment in FIG. 1.
[0032]
2, the front attachment hydraulic circuit includes the second hydraulic pump 2, the main relief valve 35, the spare direction control valve 28, and the overload relief valve units 45 and 46, as described above. The oil passages on the actuator port side of the spare directional control valve 28 in which the spare overload relief valve units 45 and 46 are provided are denoted by reference numerals 51 and 52, and the oil in the valve housing of the control valve device 5 is provided. Connection ports 53 and 54 are provided at portions where the passages 51 and 52 are open, and a pipe 56 is connected to one of the connection ports 53, and the pipe 56 is connected to a supply port 55 of the hydraulic breaker 12. The other connection port 54 is closed with a plug. The discharge port 57 of the hydraulic breaker 12 is connected to a tank 59 via a pipe 58. The pipe 56 is provided with high-pressure accumulators 63 for absorbing the pulsation of the high-pressure hydraulic pressure when the hydraulic breaker 12 is driven. The pipe 58 is provided with a filter 60 and low-pressure accumulators 64 for absorbing the pulsation of the low-pressure hydraulic pressure when the hydraulic breaker 12 is driven.
[0033]
Here, the oil passage 51, the pipe 56, and the pipe 58 located on the actuator port side of the spare directional control valve 28 constitute an actuator circuit portion of the front attachment hydraulic circuit, of which the oil passage 51 and the pipe 56 are used for directional control. The high pressure side actuator circuit portion in which the pressure oil is supplied from the valve 28 to the hydraulic breaker 12 constitutes a high pressure side actuator circuit portion, and the pipe 58 constitutes the low pressure side actuator circuit portion in which the pressure oil working in the hydraulic breaker 12 is returned to the tank 59. .
[0034]
The hydraulic breaker 12 is operated by the operation pedal 66. The operation pedal 66 is operable in a forward direction (toe side) and a rearward direction (heel side). When the hydraulic breaker 12 is mounted, a lock mechanism 66a for preventing backward movement is provided. I can do it. The spare directional control valve 28 has pressure receiving portions 28a and 28b, and when the operation pedal 66 is operated in the forward direction, an operation pilot pressure is supplied to the pressure receiving portion 28a above the spare directional control valve 28 in the drawing to control the direction. The valve 28 switches to the upper position in the figure. Accordingly, the pressure oil from the second hydraulic pump 2 passes through the direction control valve 28, flows into the hydraulic breaker 12 from the supply port 55 via the oil passage 51 and the pipe 56, and drives the hydraulic breaker 12 to perform a crushing operation. Become like The pressure oil that has worked in the hydraulic breaker 12 passes through the pipe 58, and after the dust and foreign substances are removed by the filter 60, is returned directly to the tank 59.
[0035]
The overload relief valve unit 45 has a variable relief valve 63 and a supply check valve 64. The variable relief valve 63 is mounted on the mounting port of the conventional overload relief valve provided in the valve housing of the control valve device 5 instead of the overload relief valve. The overload relief valve unit 46 is the same as the conventional one, and has a normal overload relief valve 67 and a supply check valve 68.
[0036]
The variable relief valve 63 is capable of changing a relief set pressure by operating a pilot oil pressure, and the set pressure can be switched between a high pressure and a low pressure by a set pressure changing device 65. The set pressure changing device 65 is configured as a means for turning on and off the pilot oil pressure. When the pilot oil pressure is off, the variable relief valve 63 is set to low pressure, and when the pilot oil pressure is on, the variable relief valve 63 is set to high pressure. .
[0037]
The set pressure changing device 65 has a changeover switch 71 and an electromagnetic valve 72, and the changeover switch 71 is provided in a power supply circuit 77. The primary pressure port of the solenoid valve 72 is connected to the discharge oil passage of the pilot hydraulic pump 73, and the pressure of the discharge oil passage of the pilot hydraulic pump 73 is maintained at a constant value by a relief valve 74. The secondary pressure port of the solenoid valve 72 is connected via a pipe 75 to a pressure receiving portion 76 for adjusting the set pressure of the variable relief valve 63, and the tank port is connected to the tank 59. When the changeover switch 71 is open, the solenoid valve 72 is at the position shown in the figure, the secondary pressure port is connected to the tank port, and the pressure receiving portion 76 of the variable relief valve 63 is connected to the tank 59. That is, the pressure receiving portion 76 of the variable relief valve 63 and the discharge oil passage of the pilot hydraulic pump 73 are shut off. Therefore, the pilot oil pressure to the pressure receiving portion 76 of the variable relief valve 63 is off, and the variable relief valve 63 is set to a low pressure. When the changeover switch 71 is operated and the power supply circuit 77 is closed, the solenoid valve 72 switches from the position shown in the figure, the primary pressure port is connected to the secondary pressure port, and the pressure receiving portion 76 of the variable relief valve 63 is connected to the pilot hydraulic pump 73. Is connected to the discharge oil passage. As a result, the pilot oil pressure is turned on, and the variable relief valve 63 is switched to the high pressure setting.
[0038]
Here, when the hydraulic breaker whose allowable pressure is lower than the relief pressure of the main relief valve 35 is called a low pressure hydraulic breaker, and the hydraulic breaker whose allowable pressure is higher than the relief pressure of the main relief valve 35 is called a high pressure hydraulic breaker, The low pressure setting of the relief valve 63 is set to be equal to the allowable pressure of the low pressure hydraulic breaker, and the high pressure setting of the variable relief valve 63 is set to be equal to the setting of the overload relief valve for a normal front attachment. As a result, the low pressure setting of the variable relief valve 63 is lower than the relief pressure of the main relief valve 35, and the high pressure setting of the variable relief valve 63 is higher than the relief pressure of the main relief valve 35.
[0039]
The operation pedal 66 and the changeover switch 71 are arranged in a cab 107 (see FIG. 3) of the excavator.
[0040]
FIG. 3 shows the appearance of a hydraulic shovel equipped with the hydraulic breaker 12. The hydraulic excavator has a traveling body 100, a revolving body 101, and a front working machine 102. The traveling body 100 drives left and right crawlers 100a and 100b (only one is shown) by left and right traveling motors 11 and 6 (only one is shown). Then, the revolving unit 101 is revolved on the traveling unit 100 by the revolving motor 9. The front working machine 102 has an articulated structure including a boom 103, an arm 104, and a hydraulic breaker 12, and is rotatably driven in a vertical plane by a boom cylinder 8, an arm cylinder 10, and a bucket cylinder 7, respectively. An operator cab 107 is installed on the revolving superstructure 101.
[0041]
In the hydraulic circuit device of the present embodiment configured as described above, when the allowable pressure of the hydraulic breaker 12 to be mounted is lower than the relief pressure of the main relief valve 35 of the control valve device 5, the setting pressure changing device 65 The changeover switch 71 is kept open, and the solenoid valve 72 is set to the position shown in the figure. As a result, the pilot hydraulic pressure from the pilot hydraulic pump 73 to the pressure receiving portion 76 of the variable relief valve 63 is turned off, and the variable relief valve 63 is set at a low pressure. Can be protected.
[0042]
When the allowable pressure of the hydraulic breaker 12 to be mounted is higher than the relief pressure of the main relief valve 35, the switch 71 of the set pressure changing device 65 is closed, and the electromagnetic valve 72 is switched from the position shown in the figure. As a result, the pressure receiving portion 76 of the variable relief valve 63 is connected to the discharge oil passage of the pilot hydraulic pump 73, the pilot hydraulic pressure is turned on, and the variable relief valve 63 is set to a high pressure. The excessive pressure of the hydraulic breaker 12 can be controlled by the main relief valve 35 in the inside.
[0043]
FIG. 4 shows, as a comparative example, a conventional hydraulic circuit for a front attachment in the case where the allowable pressure of the hydraulic breaker 12 to be mounted is low, with a hydraulic circuit diagram similar to FIG. In the drawing, members equivalent to those in FIG. 2 are denoted by the same reference numerals.
[0044]
The overload relief valve unit 245 of the control valve device 205 includes a normal overload relief valve 263 and a replenishment check valve 264. When the allowable pressure of the mounted hydraulic breaker 12 is lower than the relief pressure of the main relief valve 35, excessive pressure is applied to the hydraulic breaker 12 by the pressure oil from the second hydraulic pump 2, which causes a failure of the hydraulic breaker 12. Therefore, a low-pressure relief valve 290 is provided in the pipe 56, which is a high-pressure side actuator circuit part, separately from the main relief valve 35, and the low-pressure relief valve 290 protects the hydraulic breaker 12 from excessive pressure. The low pressure relief valve 290 is usually provided on the boom 103 (FIG. 3) of the hydraulic shovel.
[0045]
FIG. 5 shows, as another comparative example, a conventional hydraulic circuit for a front attachment in the case where the allowable pressure of the hydraulic breaker 12 to be mounted is high, with a hydraulic circuit diagram similar to FIG. In the drawing, members equivalent to those in FIG. 2 are denoted by the same reference numerals. 4 in that a low-pressure relief valve 290 is not provided. When the hydraulic breaker 12 having the allowable pressure higher than the relief pressure of the main relief valve 35 of the control valve device 205 is mounted, there is no problem even if the pressure control is performed by the main relief valve 35. No relief valve is installed.
[0046]
As shown in Fig. 5, the hydraulic circuit for the front attachment of the standard specification often does not have a low-pressure relief valve, so when a hydraulic breaker with a low allowable pressure is installed, the low-pressure relief valve is connected to the hydraulic source side piping on the boom. 290 and a low pressure relief valve 290 as shown in FIG. Also, once the low pressure relief valve 290 is incorporated into the front attachment hydraulic circuit, when replacing the hydraulic pressure breaker with a higher allowable pressure, the low pressure relief valve 290 is removed or a stop valve is provided before and after the relief valve, It is necessary to close the stop valve.
[0047]
As described above, in the conventional technology, it is necessary to install the low-pressure relief valve 290 in the hydraulic-source-side piping on the boom, depending on the allowable pressure of the hydraulic breaker to be mounted. Cause.
[0048]
According to the present embodiment, such a problem is solved, and the following effects are obtained.
[0049]
1. By simply operating the changeover switch 71 in the cab 107, the set pressure of the variable relief valve 63 is switched, and the same function as the presence or absence of the conventional low-pressure relief valve 290 is performed. It is not necessary to remove or open / close the stop valve, and it is possible to greatly reduce the number of assembly steps and the amount of work when the hydraulic breaker is mounted, regardless of the allowable pressure of the hydraulic breaker to be mounted.
[0050]
2. Conventionally, it is necessary to use two types of hydraulic circuits as shown in FIGS. 4 and 5 depending on the allowable pressure of the hydraulic breaker, and accordingly, there are two types of piping components, but in this embodiment, Since there is no need to change the hydraulic circuit, piping components can be unified into one type, and component management becomes easy.
[0051]
3. The variable relief valve 63 is attached to the mounting port of the conventional overload relief valve provided in the valve housing of the control valve device 5 instead of the overload relief valve, and the setting of the high pressure is equivalent to the setting of the overload relief valve. Therefore, the variable relief valve 63 also functions as a conventional overload relief valve, and the number of parts can be reduced. Further, since the variable relief valve 63 is installed at the existing mounting port, there is no need to change the valve housing of the control valve device 5.
[0052]
4. Since there is no need to install the low-pressure relief valve 290 on the boom 103, there is no need to climb the boom 103 when the low-pressure hydraulic breaker is mounted, which improves safety.
[0053]
A second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the present invention is applied to a hydraulic circuit device of a hydraulic shovel having a hydraulic circuit for a front attachment capable of replacing a hydraulic breaker and a crusher. In the figure, the same reference numerals are given to members equivalent to those shown in FIGS.
[0054]
In FIG. 6, the actuator circuit portion on the low pressure side of the hydraulic circuit for the front attachment includes pipes 58a, 58b, and 58c. The pipe 58a is connected to the discharge port 57 of the hydraulic breaker 12, and the pipe 58b is connected to the tank 59. Reference numeral 58c is connected to the connection port 54 of the control valve device 5, and a manual switching valve 81 is provided between the pipe 58a and the pipes 58b and 58c. Further, low-pressure accumulators 64, 64 are provided in a pipe 58a, and a filter 60 is provided in a pipe 58b. The manual switching valve 81 connects the pipe 58a and the pipe 58b when in the illustrated position, and connects the pipe 58a and the pipe 58c when switched from the illustrated position. The manual switching valve 81 is disposed outside the cab 107 near the control valve device 5.
[0055]
In the actuator circuit portion on the high pressure side of the hydraulic circuit for the front attachment, stop valves 82 are provided at the inlets of the high pressure accumulators 63 connected to the pipe 56.
[0056]
FIG. 7 is a circuit diagram similar to FIG. 6 when the hydraulic breaker 12 is replaced and mounted on the crusher 85. In this case, the pipe 56 and the pipe 58a are connected to the hydraulic cylinder 86 of the crusher 85. Further, the manual switching valve 81 is switched to a position where the pipe 58a and the pipe 58c are connected as shown. Further, the lock mechanism 66a of the operation pedal 66 is removed, and the operation pedal 66 can be operated in both the forward direction (toe side) and the rear direction (heel side). Accordingly, when the operation pedal 66 is operated in the forward direction, the operation pilot pressure is supplied to the pressure receiving portion 28a above the spare direction control valve 28 in the figure, and the direction control valve 28 switches to the upper position in the figure and When the pedal 66 is operated backward, the operating pilot pressure is supplied to the pressure receiving portion 28b below the spare direction control valve 28 in the drawing, and the direction control valve 28 is switched to the lower position in the drawing, and the hydraulic cylinder of the crusher 85 86 can be selectively supplied with pressure oil to either side, so that the crusher 85 can be opened and closed.
[0057]
In the hydraulic circuit device according to the present embodiment configured as described above, when the hydraulic breaker 12 is mounted, the manual switching valve 81 is set to the illustrated position, the pipes 58a and 58b are connected, and the high-pressure accumulators 63 and 63 are connected. The stop valves 82, 82 are left open. Thus, the hydraulic circuit for the front attachment has a circuit configuration equivalent to that of the first embodiment shown in FIGS. 1 and 2, and only by switching the changeover switch 71 of the setting pressure changing device 65, the hydraulic circuit breaker of the low pressure setting and the high pressure It can easily correspond to any of the set hydraulic breakers.
[0058]
Further, when replacing the hydraulic breaker 12 having a low allowable pressure with the crusher 85, the manual switching valve 81 is switched to the position connecting the pipe 58a and the pipe 58c as shown in FIG. In addition to the circuit configuration, the stop valves 82, 82 of the high-pressure accumulators 63, 63 are closed to avoid the influence of the high-pressure accumulators 63, 63 when the hydraulic cylinder 86 is driven. Further, the changeover switch 71 of the set pressure changing device 65 is closed, the solenoid valve 72 is switched from the position shown in the drawing to set the variable relief valve 63 to high pressure, and the main relief valve 35 in the control valve device 5 controls the hydraulic cylinder 86 to operate. Be able to control excessive pressure.
[0059]
When the hydraulic breaker 12 having a high allowable pressure is replaced with the crusher 85, the manual switching valve 81 is switched to a position at which the pipe 58a and the pipe 58c are connected, the lock mechanism 66a of the operation pedal 66 is removed, and the high-pressure accumulators 63, 63 are removed. Only the stop valves 82, 82 need to be closed.
[0060]
FIG. 8 shows, as a comparative example, a hydraulic circuit for a front attachment in which a conventional hydraulic breaker and a crusher can be replaced and mounted, using a hydraulic circuit diagram similar to FIG. In the drawing, members equivalent to those in FIG. 6 are denoted by the same reference numerals.
[0061]
As in the comparative example of FIG. 4, the overload relief valve unit 245 of the control valve device 205 includes a normal overload relief valve 263 and a replenishment check valve 264. A low pressure relief valve 290 is provided. This low pressure relief valve 290 is usually provided on a boom 103 (FIG. 3) of a hydraulic shovel. Further, when the crusher is mounted, the low-pressure relief valve 290 is not required, and thus stop valves 291 and 292 are provided before and after the crusher.
[0062]
In the configuration of this comparative example, when replacing the low-pressure hydraulic breaker and the crusher, it is necessary to close not only the stop valves 82 and 82 of the high-pressure accumulators 63 and 63 but also the stop valves 291 and 292 of the low-pressure relief valve 290. The time is increasing.
[0063]
According to the present embodiment, the set pressure of the variable relief valve 63 is switched only by operating the changeover switch 71 in the operator's cab 107, and the same function as the presence or absence of the conventional low-pressure relief valve 290 is performed. The installation of the low-pressure relief valve 290 and the opening and closing operations of the stop valves 291 and 292 are not required, and the operation time required for replacing the front attachment can be significantly reduced.
[0064]
In the above-described embodiment, the variable relief valve 63 is mounted on the mounting port of the conventional overload relief valve provided in the valve housing of the control valve device 5 instead of the overload relief valve. The low-pressure relief valve may be mounted instead of the low-pressure relief valve, whereby the effects 1 and 2 of the first embodiment and the effects of the second embodiment can be obtained.
[0065]
【The invention's effect】
According to the present invention, the following effects can be obtained.
[0066]
1. By simply operating the setting pressure change means, the set pressure of the variable relief valve is switched, and it performs the same function as with or without the installation of the conventional low pressure relief valve, so it is not necessary to install or remove the low pressure relief valve, and install it Regardless of the allowable pressure of the hydraulic breaker, the number of assembly steps and the amount of work when the hydraulic breaker is mounted can be greatly reduced.
[0067]
2. Conventionally, two types of hydraulic circuits had to be used depending on the allowable pressure of the hydraulic breaker, and there were two types of piping components accordingly. However, in the present invention, there is no need to change the hydraulic circuit. Parts can be unified into one type, and parts management becomes easy.
[0068]
3. A variable relief valve is attached to the mounting port of the conventional overload relief valve provided in the valve housing of the control valve device instead of the overload relief valve, and the high pressure setting is equivalent to the setting of the overload relief valve. Therefore, the variable relief valve also functions as a conventional overload relief valve, and the number of parts can be reduced. Further, since the variable relief valve is installed at the existing mounting port, there is no need to change the valve housing of the control valve device.
[0069]
4. Since there is no need to install a low-pressure relief valve on the boom, there is no need to climb on the boom when the low-pressure hydraulic breaker is installed, which improves safety.
[0070]
5. Just by operating the setting pressure change means, the set pressure of the variable relief valve is switched, and it performs the same function as with or without the installation of the conventional low pressure relief valve, so when replacing the hydraulic breaker with a low allowable pressure and the crusher This eliminates the need for installing a low-pressure relief valve and opening / closing the stop valve, thus making it possible to greatly reduce the work time required for replacing the front attachment.
[Brief description of the drawings]
FIG. 1 is a diagram showing a hydraulic circuit device of a hydraulic shovel according to a first embodiment of the present invention.
FIG. 2 is a diagram showing details of a hydraulic circuit for a front attachment in the hydraulic circuit device shown in FIG. 1;
FIG. 3 is a diagram showing an external appearance of a hydraulic shovel equipped with a hydraulic breaker.
FIG. 4 is a hydraulic circuit diagram similar to FIG. 2 showing a comparative example.
FIG. 5 is a hydraulic circuit diagram similar to FIG. 2, showing another comparative example.
FIG. 6 is a diagram illustrating a hydraulic circuit device of a hydraulic shovel according to a second embodiment of the present invention.
7 is a diagram showing details of a hydraulic circuit for a front attachment in the hydraulic circuit device shown in FIG. 6;
FIG. 8 is a hydraulic circuit diagram similar to FIG. 6, showing a comparative example.
[Explanation of symbols]
1, 2nd and 1st hydraulic pump
5 Control valve device
6-11 Hydraulic actuator
12 Hydraulic breaker
15 First valve section
16 Second valve section
21-25 directional control valve
35 Main relief valve
45, 46 Overload relief valve unit
56,58 Piping
58a, 58b, 58c Piping
59 tanks
63 High pressure accumulator
64 Low pressure accumulator
65 Filter
66 Operation pedal
63 Variable relief valve
64 Supply check valve
65 Set pressure changing device
71 Changeover switch
72 Solenoid valve
73 pilot hydraulic pump
74 relief valve
75 Piping
77 Power supply circuit
81 Manual switching valve
82 stop valve
85 crusher
100 running body
101 Revolving superstructure
102 Front work machine
103 boom
104 arms
107 cab

Claims (5)

A hydraulic breaker, which is a front attachment of a hydraulic shovel, including a hydraulic circuit for a front attachment having at least one hydraulic pump, a main relief valve for regulating a maximum discharge pressure of the hydraulic pump, and a directional control valve for the front attachment. In a hydraulic circuit device of a hydraulic shovel capable of mounting a
A variable relief valve provided in a high-pressure side actuator circuit portion in which pressure oil is supplied from the direction control valve of the front attachment hydraulic circuit to the hydraulic breaker when the hydraulic breaker is mounted,
Setting pressure changing means for switching the setting pressure of the variable relief valve to at least two stages of a low pressure and a high pressure,
A hydraulic circuit device for a hydraulic shovel, wherein a low pressure setting of the variable relief valve is lower than a relief pressure of the main relief valve, and a high pressure setting is higher than a relief pressure of the main relief valve. A hydraulic breaker, which is a front attachment of a hydraulic shovel, including a hydraulic circuit for a front attachment having at least one hydraulic pump, a main relief valve for regulating a maximum discharge pressure of the hydraulic pump, and a directional control valve for the front attachment. In a hydraulic circuit device of a hydraulic shovel, which can be mounted and can be replaced with a hydraulic breaker and a crusher,
A variable relief valve provided in a high-pressure side actuator circuit portion in which pressure oil is supplied from the direction control valve of the front attachment hydraulic circuit to the hydraulic breaker when the hydraulic breaker is mounted,
Setting pressure changing means for switching the setting pressure of the variable relief valve to at least two stages of a low pressure and a high pressure,
A hydraulic circuit device for a hydraulic shovel, wherein a low pressure setting of the variable relief valve is lower than a relief pressure of the main relief valve, and a high pressure setting is higher than a relief pressure of the main relief valve. The hydraulic circuit device for a hydraulic shovel according to claim 1 or 2,
The variable relief valve is mounted in place of the overload relief valve at the mounting port of the overload relief valve provided in the valve housing of the control valve device including the directional control valve for the front attachment, and the variable relief valve is The hydraulic circuit device for a hydraulic shovel, wherein the setting of the high pressure is equivalent to the setting of the relief pressure of the overload relief valve. The hydraulic circuit device for a hydraulic shovel according to claim 1 or 2,
The variable relief valve can change a relief set pressure by operating a pilot hydraulic pressure,
The set pressure changing unit is a unit that turns on and off the pilot oil pressure.When the pilot oil pressure is off, the variable relief valve is set to low pressure, and when the pilot oil pressure is on, the variable relief valve is set to high pressure. A hydraulic circuit device for a hydraulic excavator. The hydraulic circuit device for a hydraulic shovel according to claim 4,
The set pressure changing means has a changeover switch and an electromagnetic valve, and the changeover switch is installed in an operator cab of a hydraulic shovel, and switches the electromagnetic valve by switching the changeover switch to turn on and off the pilot hydraulic pressure. A hydraulic circuit device for a hydraulic excavator, comprising:

Images