JP2019090493A - Fluid pressure control device - Google Patents

Abstract

To improve stability of operation of a fluid pressure control device.SOLUTION: A fluid pressure control device 100 includes: a first travel control valve 20 which controls flow of hydraulic oil supplied to/discharged from a first travel motor 1; a cylinder control valve 25 which controls flow of the hydraulic oil supplied to/discharged from a hydraulic cylinder 3; a first confluence passage 17 which guides the hydraulic oil from a third drive pump P3 to the cylinder control valve 25; and a communication valve 40 with which the confluence passage 17 is connected. A contracted part 60 which provides resistance to the passing hydraulic oil is provided at a tank passage 51 communicating with a second pilot chamber 41b of the communication valve 40.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fluid pressure control device.

  Patent Document 1 discloses a 3-circuit 3-pump system as a hydraulic circuit of a construction machine. Patent Document 1 discloses a circuit configuration in which the oil of the third pump is merged into both the first and second circuits by a merging valve when an actuator operation is performed while the vehicle is traveling. The hydraulic circuit of Patent Document 1 switches the joining valve when boom raising / turning operation is performed, joins the oil of the third pump to the first circuit to which the boom cylinder belongs through the parallel passage, and the arm cylinder belongs The second control circuit is configured to shut off the oil of the third pump for the second circuit.

  In the hydraulic circuit of Patent Document 1, a pilot line in communication with a pilot hydraulic pressure source is connected to a second pilot port of the junction valve, and a first side bypass line is connected to the pilot line. The first side bypass line passes through a sub valve integrally provided to the arm direction switching valve, and is connected downstream of the sub valve to a drain line in communication with the tank.

JP, 2014-122644, A

  In the hydraulic circuit disclosed in Patent Document 1, for example, at the time of operation of the arm, a pilot pressure which is an arm operation signal is guided to a sub valve of the arm direction switching valve, and the first valve is drained by switching the sub valve. It is cut off from As a result, an arm actuation signal is input to the second pilot port of the merging valve. Therefore, the position of the merging valve is switched, and hydraulic oil is supplied to the arm hydraulic cylinder from the third pump in addition to the hydraulic oil from the second pump.

  As described above, in the hydraulic circuit of Patent Document 1, when the flow rate of hydraulic oil to the arm hydraulic cylinder runs short, for example, during combined operation of operating the arm when the vehicle is traveling, the arm direction switching valve In conjunction with the merging valve, hydraulic oil is supplied from the third pump to the arm hydraulic cylinder. As a result, an insufficient flow rate of hydraulic oil supplied to the arm hydraulic cylinder is prevented.

  However, in such a hydraulic circuit, the space for forming the oil passage and the port is limited, so the shape and arrangement of the oil passage and the port are limited. Therefore, it is difficult to accurately match the timing at which the arm direction switching valve switches and the timing at which the merging valve switches.

  Further, the supply and discharge of hydraulic oil to the arm hydraulic cylinder is controlled by the arm direction switching valve. Therefore, before the direction switching valve for arm is switched to allow the supply of hydraulic oil to the arm hydraulic cylinder, the merging valve is switched so that the hydraulic oil is supplied from the third pump to the arm hydraulic cylinder. And the load on the third pump may increase.

  The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to improve the operation stability of a fluid pressure control device.

  According to a first aspect of the present invention, there is provided a fluid pressure control device comprising: a main passage for guiding a working fluid discharged from a first pump; and a working fluid supplied to and discharged from a fluid pressure cylinder provided in the main passage and driving a load. The cylinder control valve that controls the flow, the junction passage that leads the working fluid from the second pump to the cylinder control valve, the first pilot chamber to which the pilot passage to which the pilot pressure is directed is connected, and the tank passage that communicates with the tank are connected And a second control chamber connected to the junction passage, the first control passage connected to the tank through the cylinder control valve is connected to the pilot passage, and the communication valve is A supply position for guiding the working fluid from the second pump to the cylinder control valve, and a blocking position for blocking the supply of the working fluid from the second pump to the cylinder control valve; The first control passage is shut off by the control valve, whereby the pilot pressure is introduced to the first pilot chamber and switched to the supply position, and the tank passage is provided with a resistance portion that applies resistance to the passing working fluid. It is characterized by being

  In the first aspect of the invention, the resistance portion is provided in the tank passage that communicates the second pilot chamber of the communication valve and the tank, so that the position of the communication valve can be adjusted by adjusting the resistance applied to the flow of the working fluid by the resistance portion. Can be adjusted. Therefore, since the timing of switching between the cylinder control valve and the communication valve can be made to coincide with each other with high accuracy, it is possible to suppress an increase in the load on each pump.

  The second invention further includes a travel control valve provided in the main passage for controlling the flow of working fluid supplied to and discharged from the travel motor, and the pilot passage includes a second control passage communicating with the tank through the travel control valve. The communication valve is connected, and the first control passage is shut off by the cylinder control valve and the second control passage is shut off by the travel control valve, whereby the pilot pressure is introduced to the first pilot chamber and the supply position is reached. It is characterized by switching.

  According to the second aspect of the present invention, it is possible to prevent the shortage of hydraulic oil at the time of combined operation in which the fluid pressure cylinder operates during traveling of the vehicle in which the traveling motor is driven. Therefore, the combined operation can be performed without causing a decrease in the traveling speed.

  In a third aspect of the invention, the resistance portion is a throttle portion that narrows the flow path of the tank passage.

  A fourth invention is a variable throttle configured such that the resistance given to the flow of the working fluid decreases as the communication valve switches from the blocking position to the supply position.

  In the fourth invention, after the cylinder control valve is switched to supply and discharge the working fluid to and from the fluid pressure cylinder, the communication valve can be promptly set to the supply position, and the combined operation can be performed promptly.

  A fifth aspect of the invention is characterized in that the resistance portion is a switching valve operated by the control pilot pressure, which is derived from the control pilot pressure for operating the cylinder control valve.

  In the sixth aspect of the invention, the switching valve switches from the state of being in the first communication position where the switching valve is in communication with the second pilot chamber of the communication valve and the tank, and the control pilot pressure increases from the state of the first communication position. It has a control position for applying resistance to the working fluid flowing therein, and a second communication position for switching between the control position and the second pilot chamber and the tank as the control pilot pressure increases from the control position. I assume.

  In the sixth aspect, after the cylinder control valve is switched so as to supply and discharge the working fluid to the fluid pressure cylinder, the communication valve can be promptly set to the supply position, and the combined operation can be performed promptly.

  In the seventh aspect of the invention, the switching valve opens the tank passage in the first communication position to connect the second pilot chamber to the tank chamber, and opens the tank passage in the second communication position to communicate with the second pilot chamber It communicates with the tank chamber.

  According to an eighth aspect of the invention, the switching valve has a switching pilot chamber in which the control pilot pressure is guided, and a pilot port for guiding the control pilot pressure to the switching pilot chamber, and the second pilot is transmitted through the pilot port in the first communication position. The chamber and the tank passage are communicated, and in the second communication position, the tank passage is opened to communicate the second pilot chamber with the tank chamber.

  According to the present invention, the stability of operation of the fluid pressure control device is improved.

It is the schematic which shows the structure of the fluid pressure control apparatus which concerns on 1st Embodiment of this invention. It is a sectional view of a communicating valve concerning a 1st embodiment of the present invention, and is a figure showing a state where it is in a blocking position. It is an expanded sectional view of the communicating valve concerning a 2nd embodiment of the present invention, and is a figure showing the tank passage and the throttling part circumference. It is an expanded sectional view of the communicating valve which concerns on the 1st modification of 2nd Embodiment of this invention, and is a figure corresponding to FIG. It is an expanded sectional view of the communicating valve which concerns on the 2nd modification of 2nd Embodiment of this invention, and is a figure corresponding to FIG. It is the schematic which shows the structure of the fluid pressure control apparatus which concerns on 3rd Embodiment of this invention. It is an expanded sectional view showing the communicating valve and switching valve concerning a 3rd embodiment of the present invention, and is a figure showing the state where a switching valve is in the 1st communicating position. It is the schematic which shows the structure of the fluid pressure control apparatus which concerns on the modification of 3rd Embodiment of this invention. It is an expanded sectional view which shows the communicating valve and switching valve which concern on the modification of 3rd Embodiment of this invention, and is a figure which shows the state which a switching valve is in a 1st communication position.

First Embodiment
Hereinafter, a fluid pressure control device 100 according to a first embodiment of the present invention will be described with reference to the drawings. In the following, a fluid pressure control device 100 provided in a fluid pressure control system 101 which is used in a construction machine, in particular a hydraulic shovel and which controls the flow of working fluid supplied to and discharged from a fluid pressure actuator will be described as an example.

  First, with reference to FIG. 1, an overall configuration of a fluid pressure control system 101 provided with a fluid pressure control device 100 will be described.

  The fluid pressure control system 101 drives a plurality of hydraulic pumps P1, P2, P3 for discharging hydraulic fluid as a hydraulic fluid, a tank T for storing hydraulic fluid, and a pair of left and right traveling devices (not shown) of crawler type. Hydraulic cylinder 3 as a fluid pressure cylinder for driving a driving target (not shown) such as a first traveling motor 1 and a second traveling motor 2 and a boom, an arm, or a bucket, a first traveling motor 1, a second traveling And a fluid pressure control device 100 for controlling the operation of the motor 2 and the hydraulic cylinder 3. Below, the case where hydraulic cylinder 3 drives a boom is explained to an example, and illustration and detailed explanation are omitted about a hydraulic cylinder which drives driving targets other than a boom.

  The fluid pressure control system 101 includes three hydraulic pumps, a first drive pump P1 as a first pump, a second drive pump P2, and a third drive pump P3 as a second pump. The first drive pump P1, the second drive pump P2, and the third drive pump P3 are driven by an engine (not shown) or a motor (not shown) to discharge hydraulic oil.

  Hydraulic fluid is supplied to and discharged from the first traveling motor 1 through the first supply and discharge passage 10a and the second supply and discharge passage 10b. The first traveling motor 1 is forwardly supplied with hydraulic oil from the first supply and discharge passage 10a and discharged through the second supply and discharge passage 10b, and is normally rotated, and supplied with hydraulic oil from the second supply and discharge passage 10b. The hydraulic fluid is discharged through the first supply and discharge passage 10a to reverse. Similarly, hydraulic oil is supplied to and discharged from the second travel motor 2 through the third supply and discharge passage 11a and the fourth supply and discharge passage 11b. The second travel motor 2 is forwardly supplied with hydraulic oil from the third supply and discharge passage 11a and discharged through the fourth supply and discharge passage 11b, and is supplied with hydraulic oil from the fourth supply and discharge passage 11b. The hydraulic fluid is discharged through the third supply and discharge passage 11a to reverse.

  The hydraulic cylinder 3 is a double acting cylinder having a piston 5 that divides the inside of the cylinder tube 4 into a rod side chamber 7 and a bottom side chamber 8. The piston rod 6 is connected to the piston 5. Hydraulic fluid is supplied to and discharged from the rod side chamber 7 of the hydraulic cylinder 3 through the rod side passage 12a. Hydraulic fluid is supplied to and discharged from the bottom side chamber 8 of the hydraulic cylinder 3 through the bottom side passage 12b.

  The hydraulic oil is supplied to the bottom side chamber 8 and the hydraulic oil is discharged from the rod side chamber 7, whereby the hydraulic cylinder 3 is extended to raise the boom. On the contrary, the hydraulic cylinder 3 is contracted to lower the boom by supplying the hydraulic oil to the rod side chamber 7 and discharging the hydraulic oil from the bottom side chamber 8.

  Next, a specific configuration of the fluid pressure control device 100 will be described.

  The fluid pressure control device 100 is connected to a first drive pump P1 and is supplied with hydraulic fluid from the first drive pump P1, and is connected to a second drive pump P2 and is hydraulic fluid from a second drive pump P2 And a third circuit system C3 connected to the third drive pump P3 and supplied with hydraulic oil from the third drive pump P3.

  The first circuit system C1 is provided with a first main passage 13 for guiding the hydraulic fluid discharged from the first drive pump P1 and a flow of the hydraulic fluid provided in the first main passage 13 and discharged to the first traveling motor 1 A first travel control valve 20 for controlling, and a cylinder control valve 25 provided in the first main passage 13 downstream of the first travel control valve 20 and controlling the flow of hydraulic fluid supplied to and discharged from the hydraulic cylinder 3; Equipped with

  The first main passage 13 is connected to the drain passage 14 communicating with the tank T, and guides the hydraulic oil discharged from the first drive pump P1 to the tank T.

  The first travel control valve 20 has a neutral position 20A for opening the first main passage 13, a forward rotation position 20B for rotating the first travel motor 1 in a forward direction, and a reverse position 20C for rotating the first travel motor 1 in reverse. Have. The first travel control valve 20 switches to the forward rotation position 20B when the pilot pressure is introduced to one of the pilot chambers 21a, and switches to the reverse position 20C when the pilot pressure is introduced to the other pilot chamber 21b. In a state where the pilot pressure is not introduced to any of the pair of pilot chambers 21a and 21b, the first travel control valve 20 is maintained at the neutral position 20A by the pair of centering springs 22a and 22b.

  In a state where the first travel control valve 20 is in the neutral position 20A, the first supply / discharge passage 10a and the second supply / discharge passage 10b connected to the first travel motor 1 respectively merge into the drain passage 14 with the first drain joint It communicates with the passage 14a. For this reason, the first travel motor 1 is not fed with the hydraulic oil and does not rotate. Further, a branch passage 13 a branched from the first main passage 13 is connected to the first travel control valve 20. When the first travel control valve 20 is in the neutral position 20A, the first main passage 13 is opened and the branch passage 13a is shut off.

  When the first travel control valve 20 is switched to the forward rotation position 20B, the first main passage 13 is shut off, and hydraulic oil is introduced to the first travel motor 1 through the branch passage 13a and the first supply / discharge passage 10a. Further, hydraulic oil is discharged from the first traveling motor 1 through the second supply / discharge passage 10b and the first drain merging passage 14a. Therefore, when the first travel control valve 20 is switched to the forward rotation position 20B, the first travel motor 1 rotates forward.

  When the first travel control valve 20 is switched to the reverse rotation position 20C, the first main passage 13 is shut off, and hydraulic fluid is introduced to the first travel motor 1 through the branch passage 13a and the second supply / discharge passage 10b. The hydraulic oil is discharged through the first supply / discharge passage 10a and the first drain merging passage 14a. Thus, when the first travel control valve 20 is switched to the reverse rotation position 20C, the first travel motor 1 reversely rotates.

  The cylinder control valve 25 has a neutral position 25A for opening the first main passage 13, an extension position 25B for extending the hydraulic cylinder 3, and a contraction position 25C for contracting the hydraulic cylinder 3. In the following, the extended position 25B and the retracted position 25C are collectively referred to as an "operating position".

  The cylinder control valve 25 operates by introducing a pilot pressure ("control pilot pressure" described later) from the pilot pump PP to the pair of pilot chambers 26a and 26b through the pilot valve 27. The pilot valve 27 guides the pilot pressure to one of the pair of pilot chambers 26a and 26b in accordance with the operation of the control lever 28 by the operator.

  The cylinder control valve 25 switches to the extended position 25B when the pilot pressure is introduced to one of the pilot chambers 26a, and switches to the contracted position 25C when the pilot pressure is introduced to the other pilot chamber 26b. When the pilot pressure is not led to any of the pair of pilot chambers 26a and 26b, the cylinder control valve 25 is maintained at the neutral position 25A by the pair of centering springs 27a and 27b.

  When the cylinder control valve 25 is in the neutral position 25A, the rod-side passage 12a and the bottom-side passage 12b connected to the hydraulic cylinder 3 branch off from the first main passage 13 between the first travel control valve 20 and The communication with the passage 13b is cut off. Further, at the neutral position 25A, the rod side passage 12a and the bottom side passage 12b are also disconnected from the communication with the second drain merging passage 14b joining the drain passage 14, respectively. As a result, the hydraulic cylinder 3 is blocked in the supply and discharge of the hydraulic oil, and is in a load holding state.

  When the cylinder control valve 25 is switched to the extension position 25B, the first main passage 13 is shut off, and the hydraulic cylinder 3 is led to the bottom side chamber 8 through the branch passage 13b and the bottom side passage 12b. The hydraulic oil in the rod side chamber 7 is discharged to the tank T through the rod side passage 12a and the second drain merging passage 14b. Thus, when the cylinder control valve 25 switches to the extension position 25B, the hydraulic cylinder 3 operates to extend.

  When the cylinder control valve 25 is switched to the contraction position 25C, the first main passage 13 is shut off, and the hydraulic cylinder 3 is guided to the rod side chamber 7 through the branch passage 13b and the rod side passage 12a. Further, the hydraulic oil in the bottom side chamber 8 is discharged to the tank T through the bottom side passage 12 b and the second drain merging passage 14 b. Thus, when the cylinder control valve 25 switches to the contraction position 25C, the hydraulic cylinder 3 is contracted.

  The second circuit system C2 is provided with a second main passage 15 for guiding the hydraulic fluid discharged from the second drive pump P2 and a flow of hydraulic fluid supplied to the second travel motor 2 provided in the second main passage 15. The second travel control valve 30 to control and the flow of hydraulic oil supplied to and discharged from a hydraulic cylinder provided in the second main passage 15 downstream of the second travel control valve 30 and driving a load different from the boom are controlled And a control valve 31. Since the second circuit system C2 has the same configuration as the first circuit system C1, detailed illustration and description will be omitted. The control valve 31 of the second circuit system C2 has the same configuration as the cylinder control valve 25 and controls the operation of the hydraulic cylinder in the same manner as the cylinder control valve 25. Therefore, detailed illustration and explanation of the control valve 31 are also omitted. A plurality of control valves 31 may be provided in the second circuit system C2 according to the number of hydraulic cylinders.

  The third circuit system C3 is provided downstream of the communication passage 40 for guiding the hydraulic fluid discharged from the third drive pump P3, the communication valve 40 provided in the pump passage 16, and the communication valve 40, and is different from the boom And a control valve that controls the flow of hydraulic fluid supplied to and discharged from a hydraulic cylinder that drives a load.

  The pump passage 16 is in communication with the tank T, and guides the hydraulic oil discharged from the third drive pump P3 to the tank T. Further, a relief passage 16 e communicating with the tank T through the drain passage 14 is connected upstream of the communication valve 40. A relief valve 43 is provided in the relief passage 16e. The control valve 44 in the third circuit system C3 has a configuration similar to that of the cylinder control valve 25 in the first circuit system C1, and thus detailed illustration and description will be omitted.

  Here, in the working machine, a composite operation for driving, for example, a boom may be performed while the vehicle in which the first and second traveling motors 1 and 2 rotate is traveling. However, since the first travel control valve 20 is in the forward rotation position 20B or the reverse rotation position 20C while the vehicle is traveling, the first main passage 13 is shut off by the first travel control valve 20. For this reason, during traveling of the vehicle, the cylinder control valve 25 downstream of the first travel control valve 20 is shut off from the supply of hydraulic oil from the first drive pump P1 through the first main passage 13. As a result, the flow rate of hydraulic fluid for operating the hydraulic cylinder 3 runs short.

  Therefore, in the fluid pressure control device 100, hydraulic fluid is supplied from the third drive pump P3 to the cylinder control valve 25 by the communication valve 40 in order to perform the above-described combined operation. Hereinafter, the configuration and operation of the communication valve 40 will be described. In the following, the case of combined operation of the boom driving hydraulic cylinder 3 whose operation is controlled by the first circuit system C1 will be described as an example. The same operation as in the case of the first circuit system C1 can be applied to the combined operation with the hydraulic cylinder whose operation is controlled by the second circuit system C2, and therefore the description will be omitted as appropriate. Moreover, below, the 1st travel control valve 20 is only called "travel control valve 20", and the 1st travel motor 1 is also only called "travel motor 1."

  First, the configuration of the communication valve 40 will be described with reference to FIG.

  The communication valve 40 is connected to a first merging passage 17 for guiding the hydraulic fluid from the third drive pump P3 to the cylinder control valve 25. The first merging passage 17 communicates with a branch passage 13 b branched from the first main passage 13 between the travel control valve 20 and the cylinder control valve 25.

  Further, the communication valve 40 is connected with a branch passage 19 branched from the pump passage 16 and a second junction passage 18 for guiding hydraulic fluid from the third drive pump P3 to the control valve 31 of the second circuit system C2. Be done.

  The communication valve 40 is switched in position by the movement of a spool 46 (see FIG. 2) described later. The communication valve 40 has a supply position 40A for introducing hydraulic fluid from the third drive pump P3 to the cylinder control valve 25 and a shutoff position 40B for blocking supply of hydraulic fluid from the third drive pump P3 to the cylinder control valve 25; Have. The branch passage 19 is not shut off when the communication valve 40 is in either the supply position 40A or the shutoff position 40B, and guides the hydraulic oil of the third drive pump P3 to the control valve 44 of the third circuit system C3.

  Further, the communication valve 40 has a first pilot chamber 41a, a second pilot chamber 41b, and a spring 42 as a biasing member. The communication valve 40 operates in accordance with the pressure difference between the first pilot chamber 41a and the second pilot chamber 41b.

  A pilot passage 50 is connected to the first pilot chamber 41 a, and the pilot pressure is introduced through the pilot passage 50. The pilot pressure introduced into the first pilot chamber 41a acts on the spool 46 so that the communication valve 40 switches to the supply position 40A.

  A tank passage 51 communicating with the tank T is connected to the second pilot chamber 41b. Thus, the second pilot chamber 41b is filled with the hydraulic oil at a pressure corresponding to the internal pressure of the tank T. The pressure of the second pilot chamber 41b acts on the spool 46 so as to resist the pressure of the first pilot chamber 41a. Further, the tank passage 51 is provided with a throttling portion 60 as a resistance portion for giving resistance to the hydraulic fluid passing therethrough.

  The spring 42 biases the spool 46 so that the communication valve 40 switches to the shutoff position 40B. Thus, the communication valve 40 is in the blocking position 40B when the pilot pressure is not led to the first pilot chamber 41a.

  The first control passage 52 a and the second control passage 52 b are connected to the pilot passage 50 communicating with the first pilot chamber 41 a through the common passage 52. The first control passage 52 a communicates with the tank T through the cylinder control valve 25. The second control passage 52 b communicates with the tank T through the first travel control valve 20 and the second travel control valve 30. The first control passage 52 a connected to the pilot passage 50 is connected to the cylinder control valve 25, and the second control passage 52 b is connected to the first travel control valve 20, so that the communication valve 40 becomes the first travel control valve 20. And the cylinder control valve 25. The operation of the communication valve 40 will be described in detail later. In addition to connecting the first control passage 52a to the cylinder control valve 25 of the first circuit system C1, the first control passage 52a may be in communication with the tank T through the control valve 31 of the second circuit system C2.

  Hereinafter, the specific configuration of the communication valve 40 will be described with reference to FIG. In FIG. 2, the same components as in FIG. 1 will be assigned the same reference numerals and descriptions thereof will be omitted as appropriate. Further, for convenience of explanation, as shown in FIG. 1, the pump passage 16 upstream of the communication valve 40 will be described as the "upstream pump passage 16a" and the downstream pump passage 16 as the "downstream pump passage 16b".

  As shown in FIG. 2, the communication valve 40 is attached to a valve housing 45 in which the first accommodation hole 45 a is formed, a spool 46 slidably inserted in the first accommodation hole 45 a and switching the position, and the valve housing 45 And a first cap 49a and a second cap 49b for receiving the both ends of the spool 46.

  The valve housing 45 includes a pair of upstream ports 16c communicating with the upstream pump passage 16a, a downstream port 16d communicating with the downstream pump passage 16b, a first merging port 17a communicating with the first merging passage 17, and a second merging passage 18 A second merging port 18a in communication and a common port 52c in communication with the common passage 52 are formed to open in the first accommodation hole 45a. Further, in the valve housing 45, a part of the branch passage 19 communicating with the upstream pump passage 16a and a part of the drain passage 14 communicating with the first accommodation hole 45a are formed.

  In the drain passage 14, a partition 45b is formed in which a part of the first accommodation hole 45a into which the spool 46 is inserted is formed. A part of the drain passage 14 is branched into two by the partition wall 45 b.

  A first annular groove 46a, a second annular groove 46b, a third annular groove 46c, and a fourth annular groove 46d are formed on the outer peripheral surface of the spool 46, from one axial end (left in FIG. 2) to the other 2) It is provided side by side toward the right side).

  The first pilot chamber 41 a is partitioned between the first cap 49 a and one end of the spool 46. The first cap 49 a is formed with a pilot port 49 c in communication with the pilot passage 50. The first pilot chamber 41a communicates with the pilot port 49c of the first cap 49a through the orifice 50a. Further, the spool 46 is formed with a first internal passage 47 communicating the first pilot chamber 41a and the second annular groove 46b. The first pilot chamber 41a is in constant communication with the common port 52c through the first internal passage 47 and the second annular groove 46b.

  The second pilot chamber 41 b is partitioned between the second cap 49 b and the other end of the spool 46. The spring 42 is provided in a compressed state between the second cap 49 and the other end of the spool 46, and biases the spool 46 in the direction in which the second pilot chamber 41b expands.

  The second pilot chamber 41 b always communicates with the drain passage 14 through the second internal passage 48 formed at the other end of the spool 46. The second internal passage 48 opens in the second pilot chamber 41 b and extends in the axial direction of the spool 46. The second internal passage 48 opens in the fourth annular groove 46 d of the spool 46 and is a radial passage communicating with the axial passage 48 a. And 48b. The second internal passage 48 corresponds to the tank passage 51 shown in FIG.

  A portion of the radial passage 48b is formed as an orifice to constitute the throttle portion 60 (see FIG. 1). The radial passage 48 b communicates with the drain passage 14 through the fourth annular groove 46 d and the first accommodation hole 45 a of the partition 45 b regardless of the position of the spool 46. Therefore, regardless of the position of the spool 46, the throttling portion 60 provided in the radial direction passage 48b functions as a fixed throttling that applies resistance according to the flow passage area to the flow of the hydraulic oil.

  Next, the operation of the communication valve 40 will be specifically described with reference to FIGS. 1 and 2.

  When the travel control valve 20 (and the second travel control valve 30) is at the neutral position 20A, the second control passage 52b communicates with the tank T, as shown in FIG. When the travel control valve 20 is switched to the forward rotation position 20B or the reverse rotation position 20C, the second control passage 52b is shut off from the communication with the tank T by the travel control valve 20 and closed without communicating with other passages and the like. Be done. Although illustration and detailed description are omitted, the second control passage 52b is shut off also when the second travel control valve 30 of the second circuit system C2 is switched to the operating position.

  Similarly, the first control passage 52a communicates with the tank T when the cylinder control valve 25 is in the neutral position 25A. When the cylinder control valve 25 is switched to the operating position (one of the extended position 25B and the contracted position 25C), the first control passage 52a is interrupted in communication with the tank T by the cylinder control valve 25 and is switched to another passage etc. Is closed without communication.

  Therefore, in the state where at least one of the travel control valve 20 and the cylinder control valve 25 is in the neutral position 20A, 25A (in other words, the state where at least one of the travel motor 1 and the hydraulic cylinder 3 does not operate) The pilot pressure is led to the tank T through the second control passage 52b and / or the first control passage 52a. Therefore, the communication valve 40 is brought into the blocking position 40B by the biasing force of the spring 42.

  When the communication valve 40 is in the blocking position 40B, as shown in FIG. 2, one upstream port 16c and the downstream port 16d communicate with each other through the third annular groove 46c. Thus, the upstream pump passage 16a and the downstream pump passage 16b communicate with each other, and the pump passage 16 is opened. Further, the communication between the pair of upstream ports 16 c and the first and second junction ports 17 a and 18 a is blocked by the spool 46.

  When the travel control valve 20 is switched to the forward rotation position 20B or the reverse rotation position 20C and the cylinder control valve 25 is switched to the extension position 25B or the contraction position 25C, the first control passage 52a and the second control passage 52b are respectively The communication with the tank T is cut off. Thus, the pilot pressure in the pilot passage 50 is led to the first pilot chamber 41 a of the communication valve 40.

  When the pilot pressure is introduced into the first pilot chamber 41a, the spool 46 moves in the right direction in FIG. 2 so that the volume of the first pilot chamber 41a is expanded, and the hydraulic fluid of the second pilot chamber 41b flows in the radial direction passage. The gas is discharged to the tank T through the throttling portion 60 and the drain passage 14 of the tank passage 48 b (tank passage 51). Thus, the communication valve 40 is switched to the supply position 40A.

  At the supply position 40A, the upstream port 16c and the first junction port 17a communicate with each other through the third annular groove 46c, and the upstream port 16c and the second junction port 18a communicate with each other through the first annular groove 46a. Thus, the upstream pump passage 16a and the first combined passage 17 communicate with each other, and the upstream pump passage 16a and the second combined passage 18 communicate with each other. Further, in the supply position 40A, the communication between the upstream pump passage 16a and the downstream pump passage 16b is blocked by the spool 46.

  As a result, the hydraulic oil of the third drive pump P3 is guided to the cylinder control valve 25 through the first junction passage 17, so that combined operation of simultaneously driving the traveling motor 1 and the hydraulic cylinder 3 for driving the boom becomes possible.

  As described above, the communication valve 40 switches in response to the switching of the travel control valve 20 and the cylinder control valve 25. However, in the fluid pressure control device 100, the space for forming the respective passages and ports in the valve housing 45 is limited, and the shape and layout of the passages are also limited accordingly. Therefore, it is difficult to accurately match the timing at which the travel control valve 20 and the cylinder control valve 25 are switched with the timing at which the communication valve 40 is switched.

  For example, when operating the boom while the vehicle is traveling, the communication valve 40 switches to the supply position 40A before the cylinder control valve 25 switches to the operating position and the supply of hydraulic fluid to the hydraulic cylinder 3 is permitted. The hydraulic fluid is led from the third drive pump P3 to the first junction passage 17. However, since the hydraulic oil can not be supplied to the hydraulic cylinder 3, the load of the third drive pump P3 is increased. As a result, the first and second drive pumps P1 and P2 are horsepower controlled together with the third drive pump P3 to reduce the displacement, which may lead to a decrease in the traveling speed of the vehicle.

  On the other hand, in the fluid pressure control device 100, the throttling portion 60 is provided in the radial passage 48b (tank passage 51) communicating with the second pilot chamber 41b. The communication valve 40 switches its position according to the resistance of the hydraulic fluid applied by the throttle unit 60. For this reason, the timing at which the communication valve 40 switches can be adjusted by adjusting the resistance given by the throttling portion 60, specifically, the orifice diameter and the like. That is, the timing of switching to the supply position 40A can be delayed according to the resistance provided by the throttling unit 60 as compared to the case where the throttling unit 60 is not provided. Thereby, it can be made to correspond substantially with the timing to which the cylinder control valve 25 switches. Therefore, it is possible to prevent the communication valve 40 from switching to the supply position 40A before the cylinder control valve 25 switches, and it is possible to increase the load of the third drive pump P3 and to reduce the traveling speed during combined operation. It can be prevented. In order to prevent an increase in load of the third drive pump P3 and a decrease in travel speed during combined operation, at least the communication valve 40 is switched to the supply position 40A after the cylinder control valve 25 is switched to the operation position. It may be configured to change, and it is not limited to perfect matching of the switching timing of the two.

  Next, a modification of the present embodiment will be described. The following modifications are also within the scope of the present invention, and the following modifications and each configuration of the above embodiment may be combined, or the following modifications may be combined with other embodiments described later and their modifications, It is also possible to combine the following modifications. Moreover, it is possible to combine with another modification and another embodiment similarly about the modification described in description of the said embodiment.

  In the above-described embodiment, the case has been described in which the hydraulic oil is introduced from the third drive pump P3 to the cylinder control valve 25 at the time of combined operation of operating the boom while the vehicle is traveling. Not limited to this, also in the case other than the combined operation time, in order to compensate for the shortage of the flow rate of the hydraulic fluid supplied to the hydraulic cylinder 3, the third hydraulic pump is configured to guide the hydraulic fluid to the cylinder control valve 25 May be For example, the second control passage 52b in the above embodiment may be connected to a cylinder control valve (not shown) that controls a hydraulic cylinder that operates other than the boom (for example, an arm). In this case, when the boom and the arm are simultaneously operated, the hydraulic oil is led from the third drive pump P3 to the cylinder control valve 25 to prevent the flow rate of the hydraulic oil from being insufficient. Further, the second control passage 52b may be eliminated, and the communication valve 40 may be configured to guide hydraulic fluid from the third drive pump P3 to the cylinder control valve 25 in conjunction with the single cylinder control valve 25. . As described above, the communication valve 40 may be configured to guide the hydraulic oil of the third drive pump P3 to the cylinder control valve 25 in conjunction with at least one cylinder control valve 25.

  According to the above embodiment, the following effects can be obtained.

  In the fluid pressure control device 100, the throttling portion 60 is provided in the tank passage 51 communicating the second pilot chamber 41b of the communication valve 40 with the tank T, so that the resistance given to the flow of the working fluid by the throttling portion 60 is adjusted. Thus, it is possible to adjust the timing at which the position of the communication valve 40 switches. Therefore, since the switching timings of the cylinder control valve 25 and the communication valve 40 can be made to coincide with each other with high accuracy, it is possible to suppress an increase in load of each pump and to prevent a decrease in traveling speed of the vehicle. Therefore, the operation of the fluid pressure control device 100 is stabilized.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIGS. Hereinafter, differences from the first embodiment will be mainly described, and the same components as those of the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

  In the first embodiment, the throttle portion 60 provided in the tank passage 51 is a fixed throttle. On the other hand, the second embodiment is different from the first embodiment in that the throttle unit 160 is a variable throttle in which the flow passage area changes in accordance with the position of the spool 46 of the communication valve 40. The second embodiment will be described below.

  As shown in FIG. 3, in the second embodiment, the second internal passage 48 of the spool 46 includes an axial passage 48 a communicating with the second pilot chamber 41 b and two radial passages communicating with the axial passage 48 a ( Hereinafter, the “first passage 148 a” and the “second passage 148 b” will be referred to, respectively. The first passage 148 a and the second passage 148 b are formed to be separated from each other in the axial direction of the spool 46. The first passage 148a and the second passage 148b are respectively formed as orifices 160a and 160b, as in the first embodiment. The orifices 160a and 160b formed in the first passage 148a and the second passage 148b constitute a throttle portion 160 as a variable throttle.

  In the second embodiment, the spool 46 is slidably inserted into a first accommodation hole 45a provided in the partition 45b.

  When the pilot pressure is not led to the first pilot chamber 41a and the communication valve 40 is in the shutoff position 40B, as shown in FIG. 3, the opening of the first passage 148a is blocked by the inner circumferential surface of the partition 45b. The opening of the second passage 148b is only partially blocked by the inner circumferential surface of the partition 45b. Therefore, in this state, the second pilot chamber 41b communicates with the drain passage 14 through the second passage 148b, and the flow of hydraulic fluid discharged from the second pilot chamber 41b to the drain passage 14 is controlled by the second passage 148b. The resistance according to the flow passage area of the orifice 160b is given.

  When the spool 46 is moved in the right direction in the figure by the pilot pressure of the first pilot chamber 41 a, the first passage 148 a communicates with the drain passage 14 in addition to the second passage 148 b. Therefore, in this state, the second pilot chamber 41b communicates with the drain passage 14 through the first passage 148a and the second passage 148b. As a result, the flow of hydraulic fluid discharged from the second pilot chamber 41b to the drain passage 14 is given a resistance according to the sum of the flow passage areas of the orifice 160a of the first passage 148a and the orifice 160b of the second passage 148b. Be done. That is, in this state, since the flow resistance is for two orifices, the resistance applied to the flow of the hydraulic oil becomes smaller as compared with the case where it communicates with the drain passage 14 only through the second passage 148 b.

  As described above, in the present embodiment, immediately after switching from the blocking position 40B to the supply position 40A, only the second passage 148b communicates with the drain passage 14, and the hydraulic oil flowing through the second internal passage 48 (tank passage 51) Have a relatively high resistance. Thereafter, when the spool 46 moves by a predetermined amount, both the first passage 148a and the second passage 148b communicate with the drain passage 14, and the hydraulic oil flowing through the tank passage 51 is given a relatively small resistance. In this manner, the two orifices 160a and 160b of the first passage 148a and the second passage 148b form a variable throttle in which the resistance applied to the flow of the hydraulic fluid changes in accordance with the stroke of the spool 46.

  According to the present embodiment, as in the first embodiment, the timing at which the communication valve 40 switches to the supply position 40A can be delayed according to the resistance applied by the throttle unit 160, and the cylinder control valve 25 It is possible to prevent the communication valve 40 from switching to the supply position 40A before switching.

  Further, in the fluid pressure control device 100, during the combined operation, when the cylinder control valve 25 is switched to the operating position and any one of the branch passage 13b, the bottom side passage 12b and the rod side passage 12a is communicated, the communication valve 40 is promptly made. Is preferably switched to the supply position 40A. However, in the first embodiment, since the throttling portion 60 is a fixed throttle, relatively large resistance is applied to the hydraulic oil flowing through the tank passage 51 even after the cylinder control valve 25 is switched to the operating position. . That is, even after the cylinder control valve 25 has been switched to the operating position, the communication valve 40 is maintained in a state in which it is difficult to switch to the supply position 40A.

  On the other hand, in the communication valve 40 according to the second embodiment, the throttling portion 60 is a variable throttle, and the throttling portion 160 applies as the spool 46 moves by receiving the pilot pressure of the first pilot chamber 41a. The resistance is reduced. Therefore, the communication valve 40 is promptly moved to the supply position 40A by forming the throttling portion 160 so that the resistance given to the flow of the hydraulic oil decreases in accordance with the timing at which the cylinder control valve 25 switches to the operating position. It can be switched.

  As described above, in the second embodiment, the communication valve 40 is less likely to be switched to the supply position 40A until the cylinder control valve 25 is switched to the operating position by setting the throttling portion 160 as the variable throttle. On the other hand, when the cylinder control valve 25 is switched to the operating position, the communication valve 40 is rapidly switched to the supply position 40A. Therefore, according to the second embodiment, it is possible to prevent an increase in the load of the third drive pump P3 and a decrease in traveling speed at the time of combined operation, and also to drive the hydraulic cylinder 3 quickly at the time of combined operation. .

  Next, a modification of the second embodiment will be described.

  In the above embodiment, the throttle unit 160 is configured as a variable throttle by the two orifices 160a and 160b provided in the first passage 148a and the second passage 148b. On the other hand, in order to configure the diaphragm unit 160 as a variable diaphragm, the present invention is not limited to the above configuration, and other configurations may be employed.

  For example, as in the first modification shown in FIG. 4, the narrowed portion 160 is a radial passage 161 which communicates with the axial passage 48a and extends in the radial direction of the spool 46 and opens at the outer peripheral surface. It may have a uniform channel cross-sectional area. In this case, when the communication valve 40 is in the blocking position 40B, the opening of the radial passage 161 is partially blocked by the partition wall 45b. As the spool 46 moves in the right direction in the figure under the pilot pressure of the first pilot chamber 41a, the opening area of the opening of the radial passage 161 gradually increases and is applied to the flow of hydraulic oil Resistance gradually decreases.

  Further, as in the second modified example shown in FIG. 5, the narrowed portion 160 may be a notch 162 formed on the outer peripheral surface along the axial direction of the spool 46. The notch 162 is, for example, V-shaped in cross section perpendicular to the axial direction. The notch 162 communicates with the fourth annular groove 46 d and also communicates with the second pilot chamber 41 b through the recess 165 formed in the end face of the valve housing 45. Further, the notch 162 is formed as a tapered surface 162 a whose side surface on the side of the second pilot chamber 41 b becomes smaller in depth as it approaches the second pilot chamber 41 b. When the communication valve 40 is in the blocking position 40B, the flow passage area between the tapered surface 162a of the notch 162 and the recess 165 is relatively small, and a relatively large resistance to the flow of hydraulic fluid is provided. As the spool 46 moves in the right direction in the figure under the pilot pressure of the first pilot chamber 41a, the flow passage area between the tapered surface 162a of the notch 162 and the recess 165 of the valve housing 45 gradually increases. The resistance applied to the flow of hydraulic oil gradually decreases.

  Also in the first modification and the second modification as described above, the resistance imparted to the hydraulic oil flowing through the tank passage 51 is large immediately after the communication valve 40 switches from the shutoff position 40B, and the movement of the spool 46 Resistance is reduced. Therefore, compared with the first embodiment, the hydraulic cylinder 3 can be driven more quickly in the combined operation.

  Further, in the second embodiment in which the variable throttle is configured by the orifices 160a and 160b, it is not possible to process the first and second passages 148a and 148b and the orifices 160a and 160b at one time. In addition, since the orifices 160a and 160b have relatively small diameters, processing is difficult. On the other hand, in the first modification and the second modification, the radial passage 161 and the notch 162 can be formed by one processing, and the diameter is not as small as the orifices 160a and 160b. It can be easily processed as compared with the embodiment. In addition, the resistance applied to the flow of the hydraulic oil is continuous or stepwise as the spool 46 moves by receiving the pilot pressure of the first pilot chamber 41a without being limited to the first modification and the second modification. The variable stop can have any configuration as long as it is configured to be small.

  According to the above embodiment, in addition to the effects exhibited by the first embodiment, the following effects can be achieved.

  In the communication valve 40 according to the second embodiment, since the throttling portion 160 is formed as a variable throttle, the resistance given by the throttling portion 160 as the spool 46 moves by receiving the pilot pressure of the first pilot chamber 41a. Becomes smaller. Therefore, the communication valve 40 is unlikely to switch to the supply position 40A until the cylinder control valve 25 switches to the extension position 25B or the contraction position 25C. In addition, when the cylinder control valve 25 is switched to the extension position 25B or the contraction position 25C, the communication valve 40 can be configured to be rapidly switched to the supply position 40A. Therefore, it is possible to prevent an increase in load of the third drive pump P3 and a decrease in traveling speed at the time of combined operation, and it is possible to rapidly drive the hydraulic cylinder 3 at the time of combined operation.

Third Embodiment
Next, a third embodiment of the present invention will be described with reference to FIGS. 6 and 7. Hereinafter, differences from the first embodiment will be mainly described, and the same components as those of the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

  In the first embodiment, the resistance portion is the throttling portion 60 for throttling the flow path of the tank passage 51. On the other hand, the third embodiment is different from the first embodiment in that the resistance portion is the switching valve 260 provided in the tank passage 51.

  First, the configuration of the switching valve 260 will be described with reference to the hydraulic circuit diagram of FIG.

  As shown in FIG. 6, in the switching valve 260, pilot pressure (hereinafter referred to as “control pilot pressure”) guided from the pilot valve 27 to the pilot chambers 26 a and 26 b of the cylinder control valve 25 passes through the high pressure selection valve 210. It has switching pilot room 261 guided, and switching spring 262 which biases switching spool 265 (see FIG. 7) so as to resist the thrust due to the pilot pressure of switching pilot room 261. In the switching valve 260, the switching spool 265 is moved according to the thrust of the switching pilot chamber 261 by the control pilot pressure and the biasing force of the switching spring 262, and the position is switched. Further, since the control pilot pressure for operating the cylinder control valve 25 is introduced to the switching pilot chamber 261, the switching valve 260 interlocks with the cylinder control valve 25.

  The switching valve 260 switches from the state of being in the first communication position 260A for communicating the second pilot chamber 41b of the communication valve 40 and the tank T with the first communication position 260A by the increase in the control pilot pressure and the tank passage. The second pilot chamber 41b of the communication valve 40 and the tank T are switched by the holding position 260B as a throttling position for applying resistance to the hydraulic oil flowing through the cylinder 51 and the control pilot pressure increasing from the holding position 260B. And a second communication position 260C communicating the That is, as the control pilot pressure increases, the switching valve 260 switches in the order of the first communication position 260A, the holding position 260B, and the second communication position 260C.

  When the supply of control pilot pressure to switching pilot chamber 261 is shut off, switching valve 260 is maintained at first communication position 260 A by switching spring 262.

  In the holding position 260 B, the tank passage 51 is shut off by the switching valve 260. As a result, since the hydraulic oil is not discharged from the second pilot chamber 41b, the communication valve 40 is not switched to the supply position 40A when the switching valve 260 is in the holding position 260B. In the present specification, “applying resistance to the hydraulic oil flowing through the tank passage 51” means closing the tank passage 51 as in the state where the switching valve 260 is in the holding position 260B, and the second pilot chamber This means that the communication between the tank 41b and the tank T is completely cut off. Note that instead of the holding position 260B, the communication between the second pilot chamber 41b and the tank T is not completely blocked, and the flow passage area of the tank passage 51 is reduced compared to the first and second communication positions 260A and 260C. It may be a throttling position that provides a large resistance to the flow of hydraulic oil. Thus, the control position includes both the holding position 260B and the aperture position.

  Next, a specific configuration of the switching valve 260 will be described.

  As shown in FIG. 7, the switching valve 260 seals the switching spool 265 slidably inserted in the second accommodation hole 270 formed in the second cap 49 b of the communication valve 40 and the second accommodation hole 270. And a plug 280. The switching pilot chamber 261 is partitioned between one end of the switching spool 265 and the plug 280. The switching spring 262 is provided in a compressed state in a spring accommodating chamber 270 a partitioned between the other end of the switching spool 265 and the bottom of the second accommodating hole 270.

  The second cap 49b includes a first connection passage 271 for communicating the second pilot chamber 41b with the second accommodation hole 270, and a second connection passage 272 for communicating the spring accommodation chamber 270a with the tank T. It is formed. The second connection passage 272 communicates with the drain passage 14 through a third connection passage 273 formed in the valve housing 45 of the communication valve 40. The first connection passage 271, the second connection passage 272, and the third connection passage 273 constitute a tank passage 51 (see FIG. 6). Further, a fourth connection passage 274 which is provided closer to the plug 280 than the first connection passage 271 and communicates the second pilot chamber 41b with the second accommodation hole 270 is further formed in the second cap 49b.

  The plug 280 is formed with a pilot port 280 a for guiding the control pilot pressure to the switching pilot chamber 261 of the switching valve 260.

  The switching spool 265 is formed with an annular first communication passage 265a, a second communication passage 265b as an internal passage communicating the first communication passage 265a and the spring accommodating chamber 270a, and an annular third communication passage 265c. Be done. Further, a shaft portion 267 supporting the switching spring 262 is provided at an end portion of the switching spool 265 facing the spring accommodation chamber 270a. A radially extending slit 268 is formed on the end face of the switching spool 265 facing the plug 280.

  In a state where the control pilot pressure is not led to the switching pilot chamber 261 of the switching valve 260, the switching valve 260 is in the first communication position 260A. In the first communication position 260A, as shown in FIG. 7, the second pilot chamber 41b communicates with the pilot port 280a through the fourth connection passage 274, the third communication passage 265c, the switching pilot chamber 261, and the slit 268. Thus, the second pilot chamber 41 b communicates with the tank T through the pilot valve 27. In the first communication position 260A, the communication between the first connection passage 271 and the spring accommodating chamber 270a is blocked by the switching spool 265.

  When the control pilot pressure is introduced to the switching pilot chamber 261 of the switching valve 260, the switching valve 260 is switched to the holding position 260B. In the holding position 260B, the communication between the fourth connection passage 274 and the switching pilot chamber 261 is blocked by the switching spool 265, and the communication between the second pilot chamber 41b and the pilot port 280a is blocked. Further, also in the holding position 260B, the switching spool 265 cuts off the communication between the first connection passage 271 and the spring accommodating chamber 270a. Therefore, the communication between the second pilot chamber 41 b of the communication valve 40 and the tank T is shut off by the switching valve 260.

  When the control pilot pressure introduced to the switching pilot chamber 261 increases from the state of the holding position 260B, the switching spool 265 moves in the left direction in the drawing, and the switching valve 260 is switched to the second communication position 260C. In the second communication position 260C, the first connection passage 271 and the first communication passage 265a communicate with each other, and the second pilot chamber 41b receives the first connection passage 271, the first communication passage 265a, the second communication passage 265b, and the spring accommodation. It communicates with the drain passage 14 through the chamber 270 a, the second connection passage 272, and the third connection passage 273. Thus, the tank passage 51 is opened, and the hydraulic oil in the second pilot chamber 41b is discharged to the tank T.

  As described above, the switching valve 260 operates in conjunction with the cylinder control valve 25 by the control pilot pressure for operating the cylinder control valve 25, and becomes the holding position 260B at the beginning when the cylinder control valve 25 switches to the operating position. Therefore, at the initial stage when the cylinder control valve 25 switches to the operating position, it is possible to prevent the communication valve 40 from being in the supply position 40A before the cylinder control valve 25 switches.

  Further, the switching valve 260 changes from the holding position 260B to the second communication position 260C as the control pilot pressure increases. Therefore, the communication valve 40 can be rapidly switched to the supply position 40A by configuring the switching valve 260 to be in the second communication position 260C immediately after the cylinder control valve 25 is switched to the operation position. Specifically, the biasing force of the switching spring 262, the first communication passage 265a, and the first connection passage are set such that the switching valve 260 is brought into the second communication position 260C immediately after the cylinder control valve 25 is switched to the operating position. The relative position with 271 (in other words, the stroke amount of the switching spool 265 until the both communicate) may be configured. As a result, the hydraulic cylinder 3 can be rapidly driven at the time of combined operation.

  Further, since the switching valve 260 completely shuts off the tank passage 51 by the holding position 260B, the switching of the communication valve 40 can be reliably prevented.

  Next, a modification of the present embodiment will be described.

  In the above embodiment, the switching valve 260 causes the second pilot chamber 41b of the communication valve 40 to communicate with the tank T through the pilot port 280a formed in the plug 280 at the first communication position 260A. That is, when the switching valve 260 is in the first communication position 260A, the second pilot chamber 41b of the communication valve 40 does not communicate with the tank T through the tank passage 51 and the drain passage 14. On the other hand, as shown in FIG. 8, the switching valve 260 is configured to allow the second pilot chamber 41b of the communication valve 40 and the tank T to be communicated through the tank passage 51 at any of the first communication position 260A and the second communication position 260C. It may be in communication. Hereinafter, this will be specifically described with reference to FIGS. 8 and 9.

  As shown in FIG. 9, in the switching spool 265 according to the modification, the first connection passage 271 and the spring accommodating chamber 270a are in direct communication with each other at the first communication position 260A. Further, in the switching spool 265 according to the modification, the third communication passage 265 c and the fourth connection passage 274 are not formed. In such a modification, in the first communication position 260A, the second communication first connection passage 271 and the spring accommodation chamber 270a directly communicate with each other, and the tank passage 51 is opened similarly to the second communication position 260C. When the switching valve 260 is switched to the holding position 260 B, the switching spool 265 cuts off direct communication between the first connection passage 271 and the spring accommodating chamber 270 a. Further, in this state, the communication between the first connection passage 271 and the first communication passage 265a is also blocked. When the switching valve 260 switches to the second communication position 260C, as in the third embodiment, the first connection passage 271 and the first communication passage 265a communicate with each other, and the second pilot chamber 41b communicates with the tank T. Do. Even with such a modification, the same effect as that of the third embodiment can be obtained. Further, in the above embodiment, the third communication passage 265c is formed on the switching spool 265 on the plug 280 side of the first communication passage 265a, and the fourth connection passage is connected to the second cap 49b so as to communicate with the third communication passage 265c. 274 are formed. For this reason, in the said embodiment, the increase in processing cost and the enlargement of the switching spool 265 and the 2nd cap 49b are caused. On the other hand, in the modification shown in FIGS. 8 and 9, since the third communication passage 265c and the fourth connection passage 274 are not formed, the processing cost can be reduced and the switching valve can be miniaturized. As described above, from the viewpoint of cost reduction and downsizing, it is desirable that the tank passage 51 be opened at any of the first communication position 260 a and the second communication position 260 c as in the present modification.

  According to the above embodiment, in addition to the effects exhibited by the first embodiment, the following effects can be achieved.

  According to the third embodiment, the switching valve 260 operates in conjunction with the cylinder control valve 25 by the control pilot pressure for operating the cylinder control valve 25, and the cylinder control valve 25 switches to the extension position 25B or the contraction position 25C. The holding position 260B is initially set. Therefore, at the initial stage when the cylinder control valve 25 switches to the extension position 25B or the contraction position 25C, it is possible to prevent the communication valve 40 from being in the supply position 40A before the cylinder control valve 25 switches.

  Further, the switching valve 260 is configured to supply the communication valve 40 quickly by configuring the switching valve 260 to be in the second communication position 260C immediately after the cylinder control valve 25 is switched to the extension position 25B or the contraction position 25C. It is possible to switch to position 40A. As a result, the hydraulic cylinder 3 can be rapidly driven at the time of combined operation.

  Further, since the switching valve 260 completely shuts off the tank passage 51 by the holding position 260B, the switching of the communication valve 40 can be reliably prevented.

  Hereinafter, the configuration, operation, and effects of the embodiment of the present invention will be collectively described.

  The fluid pressure control device 100 is provided with a first main passage 13 for guiding the hydraulic fluid discharged from the first drive pump P1 and a hydraulic fluid supplied to the hydraulic cylinder 3 provided in the first main passage 13 and driving a load. The first pilot chamber 41a is connected to a cylinder control valve 25 for controlling the flow of the fluid, a first junction passage 17 for guiding hydraulic fluid from the third drive pump P3 to the cylinder control valve 25 and a pilot passage 50 for guiding a pilot pressure. And the second pilot chamber 41b to which the tank passage 51 communicating with the tank T is connected, and the communication valve 40 to which the first junction passage 17 is connected; A first control passage 52a in communication with the tank T through the valve 25 is connected, and the communication valve 40 is connected to the third control chamber according to the pressure difference between the first pilot chamber 41a and the second pilot chamber 41b. The cylinder control valve has a supply position 40A for introducing hydraulic fluid from the dynamic pump P3 to the cylinder control valve 25, and a shutoff position 40B for shutting off the supply of hydraulic fluid from the third drive pump P3 to the cylinder control valve 25. 25 cuts off the first control passage 52a to introduce the pilot pressure into the first pilot chamber 41a, switch to the supply position 40A, and apply resistance to the hydraulic fluid passing through the tank passage 51. The parts (throttle parts 60, 160, switching valve 260) are provided.

  In this configuration, the resistance portion (the throttling portions 60 and 160, the switching valve 260) is provided in the tank passage 51 communicating the second pilot chamber 41b of the communication valve 40 and the tank T. The timing at which the position of the communication valve 40 switches can be adjusted by adjusting the resistance that the switching valve 260 applies to the flow of hydraulic fluid. Therefore, since the timing of switching between the cylinder control valve 25 and the communication valve 40 can be made to coincide with each other with high accuracy, it is possible to suppress an increase in the load on each pump. Therefore, the stability of the operation of the fluid pressure control device 100 is improved.

  The fluid pressure control device 100 further includes a first travel control valve 20 provided in the first main passage 13 upstream of the cylinder control valve 25 and controlling the flow of hydraulic fluid supplied to and discharged from the first travel motor 1. A second control passage 52b communicating with the tank T through the travel control valve 20 is connected to the pilot passage 50, and the communication control valve 40 blocks the first control passage 52a by the cylinder control valve 25 and the travel control valve. As the second control passage 52b is shut off by 20, the pilot pressure is introduced to the first pilot chamber 42a and switched to the supply position 40A.

  In this configuration, it is possible to prevent the shortage of hydraulic oil at the time of combined operation in which the hydraulic cylinder 3 operates during traveling of the vehicle in which the first traveling motor 1 is driven. Therefore, the combined operation can be performed without causing a decrease in the traveling speed.

  In the first and second embodiments, the resistance portion is the throttling portions 60 and 160 for throttling the flow path of the tank passage 51.

  Further, in the second embodiment, the throttling unit 160 is a variable throttle configured so that the resistance applied to the flow of the hydraulic oil decreases as the communication valve 40 switches from the shutoff position 40B to the supply position 40A.

  In this configuration, after the cylinder control valve 25 is switched to supply and discharge the hydraulic oil to and from the hydraulic cylinder 3, the communication valve 40 can be promptly set to the supply position 40A, and the combined operation can be performed promptly. .

  Further, in the third embodiment, the resistance portion is the switching valve 260 which is led by the control pilot pressure for operating the cylinder control valve 25 and operated by the control pilot pressure.

  Further, in the third embodiment, the control pilot pressure is increased from the state of the first communication position 260A communicating with the second pilot chamber 41b of the communication valve 40 and the tank T, and the first communication position 260A. Therefore, the control pilot pressure is switched from the control position (retention position 260B) to the control position (retention position 260B) for giving resistance to the working fluid flowing through the tank passage 51 by switching, thereby switching the second position. A second communication position 260C for communicating the pilot chamber 41b with the tank T is provided.

  In this configuration, after the cylinder control valve 25 is switched to supply and discharge the hydraulic oil to and from the hydraulic cylinder 3, the communication valve 40 can be promptly set to the supply position 40A, and the combined operation can be performed promptly. .

  In the third embodiment, the switching valve 260 opens the tank passage 51 at the first communication position 260A to communicate the second pilot chamber 41b with the tank T chamber, and the tank passage 51 at the second communication position 260C. To communicate the second pilot chamber 41b with the tank T chamber.

  Further, in the modification according to the third embodiment, the switching valve 260 has the switching pilot chamber 261 to which the control pilot pressure is guided, and the pilot port 280 a which guides the control pilot pressure to the switching pilot chamber 261. In the communication position 260A, the second pilot chamber 41b is communicated with the tank passage 51 through the pilot port 280a, and in the second communication position 260C, the tank passage 51 is opened to communicate the second pilot chamber 41b with the tank T chamber. .

  As mentioned above, although the embodiment of the present invention was described, the above-mentioned embodiment showed only a part of application example of the present invention, and in the meaning of limiting the technical scope of the present invention to the concrete composition of the above-mentioned embodiment. Absent.

  1, 2 ... traveling motor, 3 ... hydraulic cylinder (fluid pressure cylinder), 13 ... first main passage (main passage), 15 ... second main passage (main passage), 17 ... first combined passage (merged passage), 18 ... merging passage (joining passage), 20 ... first travel control valve (travel control valve), 25 ... cylinder control valve, 30 ... second travel control valve (travel control valve), 40 ... communication valve, 40A ... supply position 40B: blocking position 41a: first pilot chamber 41b: second pilot chamber 50: pilot passage 51: tank passage 52a: first control passage 52b: second control passage 60: throttle portion (resistance Part), 160: throttle part (resistance part) 260: switching valve (resistance part) 260A: first communication position 260B: holding position (control position) 260C: second communication position, 261 Switching pilot chamber, 280a ... pilot port, 100 ... hydraulic control device, P1 ... first driving pump (first pump), P3 ... third driven pump (second pump), T ... tank

Claims (8)

A main passage for guiding the working fluid discharged from the first pump;
A cylinder control valve provided in the main passage for controlling the flow of working fluid supplied to and discharged from a fluid pressure cylinder for driving a load;
A merging passage for leading the working fluid from the second pump to the cylinder control valve;
It has a first pilot chamber to which a pilot passage to which a pilot pressure is introduced is connected, and a second pilot chamber to which a tank passage communicating with a tank is connected, and a communication valve to which the merging passage is connected. ,
A first control passage, which communicates with the tank through the cylinder control valve, is connected to the pilot passage,
The communication valve has a supply position for guiding the working fluid from the second pump to the cylinder control valve, and a blocking position for blocking the supply of the working fluid from the second pump to the cylinder control valve. When the cylinder control valve shuts off the first control passage, the pilot pressure is guided to the first pilot chamber and switched to the supply position,
The fluid pressure control device according to claim 1, wherein the tank passage is provided with a resistance portion that applies resistance to the working fluid passing therethrough. The travel control valve further includes a travel control valve provided in the main passage upstream of the cylinder control valve and controlling a flow of working fluid supplied to and discharged from the travel motor.
A second control passage communicating with the tank through the travel control valve is connected to the pilot passage.
The pilot pressure is introduced to the first pilot chamber by the communication control valve blocking the first control passage by the cylinder control valve and blocking the second control passage by the travel control valve. The fluid pressure control device according to claim 1, wherein the supply position is switched.   The fluid pressure control device according to claim 1, wherein the resistance portion is a throttling portion for throttling a flow path of the tank passage.   4. The variable throttle according to claim 3, wherein the throttle portion is a variable throttle configured so that the resistance applied to the flow of the working fluid decreases as the communication valve switches from the blocking position to the supply position. The fluid pressure control device as described.   The fluid pressure control device according to claim 1 or 2, wherein the resistance portion is a switching valve operated by the control pilot pressure which is led by a control pilot pressure for operating the cylinder control valve. The switching valve is
A first communication position in communication with the second pilot chamber of the communication valve and the tank;
A control position that applies resistance to a working fluid that is switched by changing the control pilot pressure from the state of the first communication position by increasing the control pilot pressure;
The control method according to claim 5, further comprising: a second communication position in which the second pilot chamber is communicated with the tank by switching from the state of the control position as the control pilot pressure increases. Fluid pressure control device.   The switching valve opens the tank passage in the first communication position to connect the second pilot chamber to the tank, and opens the tank passage in the second communication position to open the second pilot chamber The fluid pressure control device according to claim 6, wherein the fluid pressure control device communicates with the tank.   The switching valve has a switching pilot chamber in which the control pilot pressure is guided, and a pilot port for guiding the control pilot pressure to the switching pilot chamber, and the second communication valve is provided through the pilot port at the first communication position. The fluid pressure according to claim 6, wherein the pilot chamber and the tank passage are communicated with each other, and the tank passage is opened in the second communication position to communicate the second pilot chamber with the tank. Control device.

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