JP2007254055A - Hydraulic circuit of winch for crane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic circuit of a winch for a crane capable of separately using a one-pump one-motor independent circuit system and a two-pump merging series circuit system according to content of work or the like. <P>SOLUTION: The hydraulic circuit of the winch for the crane makes the two-pump merging series circuit by merging a delivery pressure oil of the two hydraulic pump by two control valves according to operation of operation levers 21, 23 to feed it to the two hydraulic motors respectively. Further, the hydraulic circuit is provided with a pilot pressure control means 40 capable of retaining a second speed spool of the respective control valves to a neutral position regardless of operation of an operation lever by controlling a primary pressure or a secondary pressure of respective remote control valves 22, 24. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydraulic circuit for a crane winch for driving two winches installed in a mobile crane or the like.

  Generally, in a mobile crane, two winches, a main winding winch and an auxiliary winding winch, are mounted. As a hydraulic circuit for driving these two winches using two hydraulic motors and two hydraulic pumps, two types of hydraulic circuits are known as disclosed in, for example, Patent Document 1.

  As shown in FIG. 17, the one circuit system is such that the hydraulic oil discharged from the first hydraulic pump 3 is supplied to the hydraulic motor 1 for the main winding winch, and the second hydraulic pump 4 is supplied to the hydraulic motor 2 for the auxiliary winding winch. This is a so-called 1-pump 1-motor independent circuit system in which the discharge pressure oil is independently supplied through control valves 5 and 6, respectively.

  In addition, as shown in FIG. 18, the discharge pressure of the first and second hydraulic pumps 3 and 4 for the hydraulic motor 1 for the main winding winch and the hydraulic motor 2 for the auxiliary winding winch, respectively, is another circuit system. So-called two pumps that supply oil through the first and second control valves 11 and 12 in accordance with the operation of the operation levers 21 and 22 for the main winding winch or the auxiliary winding winch (see FIG. 19) It is a merging series circuit system. In this case, the first control valve 11 comprises a series circuit of a first-speed spool 13 for the main winding winch and a second-speed spool 14 for the auxiliary winding winch, and the second control valve 12 is for the main winding winch. A two-speed spool 15 and a supplementary winch first-speed spool 16 are constituted by a series circuit. Here, the series circuit is a connection-type hydraulic circuit that sends the return oil of the main winding winch hydraulic motor 1 that is the upstream actuator to the auxiliary winding winch hydraulic motor 2 that is the downstream actuator.

The first-speed spool 13 for the main winding winch and the second-speed spool 15 are both stroked by the secondary pressure of the remote control valve 22 operated by the operation lever 21 for the main winding winch as shown in FIG. Further, the first-speed spool 16 and the second-speed spool 14 for the auxiliary winding winch are stroked by the secondary pressure of the remote control valve 24 operated by the operation lever 23 for the auxiliary winding winch as shown in FIG. is there. Each of the two-speed spools 14 and 15 is configured to start a stroke at a pressure higher than the hydraulic pilot pressure at which the first-speed spools 13 and 16 perform a full stroke. In FIG. 19, 26 is a pilot hydraulic pressure source, and 27 is a tank.
No. 7-30629 (2nd page, Fig. 8-9)

  By the way, when comparing the 1-pump 1-motor independent circuit system and the 2-pump merging series circuit system, the 2-pump merging series circuit system is superior in that a high output can be secured. In the conventional mobile crane, This two-pump merging series circuit system is often used. However, in the case of the two-pump merging series circuit system, since it is a connection system in which the return oil of one hydraulic motor 1 is sent to the other hydraulic motor 2, both hydraulic motors 1 and 2 have a drawback of affecting each other. There is. For this reason, there is a demand to use the 1-pump 1-motor independent circuit system and the 2-pump merging series circuit system in accordance with the work contents.

  The present invention has been made in view of the above points. The subject of the present invention is to improve the pilot pressure control system of the control valve in the two-pump merging series circuit system, and according to the work contents and the like. Therefore, the hydraulic circuit of the winch for cranes which can use properly the 1 pump 1 motor independent circuit system and the 2 pump confluence series circuit system is provided.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a hydraulic circuit of a crane winch, wherein a first hydraulic motor that drives a first winch, a second hydraulic motor that drives a second winch, First and second hydraulic pumps, and first and second control valves for supplying the first and second hydraulic motors with the discharge pressure oil of both hydraulic pumps according to the operation of the operation lever. And the first control valve is operated by a first winch first speed spool that is stroked by a secondary pressure of a first remote control valve operated by a first operation lever and a second operation lever. The second winch 2-speed spool that strokes with the secondary pressure of the remote control valve is constituted by a series circuit, and the second control valve is operated by the first operating lever. A series circuit of a first winch 2-speed spool that strokes with the secondary pressure of one remote control valve and a second winch 1-speed spool that strokes with the secondary pressure of the second remote control valve operated by the second operating lever It is assumed that each of the two-speed spools is configured to start a stroke at a pressure higher than the hydraulic pilot pressure at which the first-speed spool makes a full stroke. In addition, by controlling the primary pressure or the secondary pressure of each remote control valve, a configuration is provided with pilot pressure control means capable of holding the second speed spool of each control valve in the neutral position regardless of the operation of the operation lever. To do.

  In this configuration, when the 2-speed spool of each control valve is held at the neutral position by the pilot pressure control means regardless of the operation of the operation lever, the pressure oil is supplied to the hydraulic motor through the 2-speed spool of each control valve. Thus, the hydraulic oil is supplied to each hydraulic motor only through the first-speed spool of the corresponding control valve, and a one-pump one-motor independent circuit system is realized. On the other hand, when the pilot control means does not hold the second-speed spool of each control valve in the neutral position, the discharge pressure oil of the first and second hydraulic pumps is controlled by the first and second controls according to the operation of the operation lever. It joins through a valve and is supplied to each hydraulic motor, and a two-pump joining series circuit system is realized. Therefore, the 1-pump 1-motor independent circuit system and the 2-pump merging series circuit system can be realized by appropriately changing the pilot pressure control means according to the work contents. In addition, the pilot pressure control means controls the primary pressure or the secondary pressure of each remote control valve so that the second speed spool of each control valve can be held in the neutral position. There is no need to change, and implementation becomes easy.

  The invention according to claim 2 provides a specific form of the pilot pressure control means in the hydraulic circuit for the crane winch according to claim 1. That is, the pilot pressure control means is configured to have a two-speed shut-off switching valve provided in each pilot pipe line communicating from each remote control valve to the pilot operating portion of the valve section of the two-speed spool of the control valve. The transmission position for transmitting the secondary pressure of the remote control valve to the pilot operating section of the valve section of the control valve's 2-speed spool and the transmission of this secondary pressure are shut off and the pilot operating section is connected to the tank. The structure is provided so as to be switchable to the blocking position. In this configuration, a plurality of two-speed shut-off switching valves provided in the pilot line of the control system of the hydraulic circuit are respectively switched to the shut-off position, and the pilot operating portion of the valve section of the two-speed spool of the control valve is switched from each remote control valve. By interrupting the transmission of the secondary pressure to the control valve, the second speed spool of each control valve is reliably held in the neutral position regardless of the operation of the operation lever.

  According to a third aspect of the present invention, in the hydraulic circuit for a crane winch according to the second aspect, each of the two-speed shut-off switching valves is controlled by hydraulic pressure, and the pilot pressure control means is The two-speed shut-off switching valves are configured to have a selection switching valve that collectively switches using a pilot pressure source. In this configuration, a plurality of two-speed shut-off switching valves can be switched at once using a pilot pressure source by a selection switch valve provided in the control system of the hydraulic circuit in the same manner as the two-speed shut-off switching valve.

  According to a fourth aspect of the present invention, in the hydraulic circuit for a crane winch according to the second or third aspect, the first and second hydraulic motors are both of a variable displacement type, and each of the two-speed shut-off switching units is used. When switching the valve from the shut-off position to the transmission position, the capacity of each hydraulic motor is maximized at the same time. In this configuration, the capacity of the first and second hydraulic motors is maximized at the same time when each of the two-speed cutoff switching valves is switched from the cutoff position to the transmission position, that is, when the two-pump merging series circuit system is changed. The maximum output is demonstrated by the motor.

  Here, when only one of the first and second hydraulic motors is operated in the two-pump merging series circuit system, the maximum rotation speed is the maximum rotation of each hydraulic motor in the one-pump / one-motor independent circuit system. Since it becomes twice the speed, there is a risk that when changing this circuit system, a speed change occurs and the operation becomes uncomfortable. In order to cope with this, the invention according to claim 5 is the hydraulic circuit of the winch for crane according to claim 2 or 3, wherein both of the first and second hydraulic motors are of a variable capacity type, and When switching each of the second speed shut-off switching valves from the shut-off position to the transmission position, the capacity on the small capacity side of each hydraulic motor is simultaneously doubled. In this configuration, the capacity on the small capacity side of the first and second hydraulic motors is doubled at the same time when switching each 2-speed shut-off switching valve from the shut-off position to the transmission position, that is, when changing to the two-pump confluence series circuit system. Thus, the maximum rotational speed of each hydraulic motor is reduced to ½, so that the maximum rotational speed of the hydraulic motor is the same in the 1-pump 1 motor independent circuit system and the 2-pump merging series circuit system.

  The inventions according to claims 6 and 7 each provide another specific form of the pilot pressure control means in the hydraulic circuit of the crane winch according to claim 1. That is, the invention according to claim 6 includes the electromagnetic proportional pressure reducing valve provided in each of the pilot lines communicating with the pilot pressure control means from each remote control valve to the pilot operating portion of the valve section of the second speed spool of the control valve. Each electromagnetic proportional pressure reducing valve is configured to hold the second speed spool in the neutral position by reducing the secondary pressure of the remote control valve to a pressure lower than the pressure value at which the second speed spool starts the stroke. Further, in the invention according to claim 7, the pilot control means is configured to have at least one electromagnetic proportional pressure reducing valve provided in a pilot line communicating from the pilot hydraulic power source to the remote control valve, and the electromagnetic proportional pressure reducing valve is The primary pressure of the remote control valve is reduced, and the secondary pressure is reduced to a pressure lower than the pressure value at which the second-speed spool starts the stroke, thereby holding the secondary spool in the neutral position.

  The invention according to claim 8 is the hydraulic circuit for a winch for crane according to claim 3, further comprising four constant ratio pressure reducing valves for reducing the secondary pressure of each remote control valve at a specific ratio, and the selective switching valve. When each two-speed shut-off switching valve is switched to the transmission position, the secondary pressure of each remote control valve is transmitted to the pilot operating section of the valve section of the first-speed spool of the control valve. Four secondary pressures for transmitting the secondary pressure of each constant ratio pressure reducing valve to the pilot operating portion of the valve section of the first speed spool of the control valve when the speed cutoff switching valve is switched to the cutoff position. It is set as the structure provided with a switching valve. In this configuration, when each of the two-speed shut-off switching valves is switched to the shut-off position by the selection switch valve, that is, when the 1-pump 1-motor independent circuit system is selected, 2 of the remote control valves operated by the operation lever. Since the secondary pressure is reduced by the constant ratio pressure reducing valve and this reduced secondary pressure is transmitted to the pilot operating portion of the valve section of the first speed spool of the control valve, the control valve 1 associated with the operation of the operating lever The change in stroke of the high speed spool becomes more gradual than in the case of the two-pump merge series circuit system, and accordingly, the invalid stroke area of the operation lever due to the neutral position of the second speed spool of the control valve can be reduced.

  In the hydraulic circuit for the crane winch according to claim 8, the operation amount of the operation lever corresponding to the stroke start point of the first-speed spool is larger in the 1-pump 1-motor independent circuit system than in the 2-pump confluence series circuit system. Thus, the stroke start point of the first-speed spool with respect to the operation of the operation lever is delayed. The inventions according to claims 9 and 10 are for improving this.

  That is, the invention according to claim 9 is the hydraulic circuit of the winch for crane according to claim 8, wherein the valve section of the first speed spool of the control valve has two pilot operation portions in each direction, and The spool stroke is determined by the sum of the pilot pressures acting on both the operating sections. Further, when each of the two-speed shut-off switching valves is switched to the shut-off position by the selection switching valve, the control lever For shifting four spool stroke start points for transmitting a predetermined pressure from the pilot hydraulic power source to one pilot operating portion in each direction in the valve section of the first speed spool of the control valve when the remote control valve is operated by It is set as the structure provided with a switching valve. In this configuration, when each of the 2-speed cutoff switching valves is switched to the cutoff position by the selection switching valve, that is, when the 1-pump 1-motor independent circuit system is selected, the 1st speed of the control valve is operated by operating the operation lever. A predetermined pressure is additionally transmitted to the pilot operating section of the valve section of the spool through the spool stroke start point shift switching valve, so that the stroke start point of the first-speed spool of the control valve with respect to the operation of the operation lever is accelerated accordingly. It is almost the same as the case of the two-pump confluence series circuit system.

  According to a tenth aspect of the present invention, in the hydraulic circuit for a crane winch according to the eighth aspect, when each of the two-speed shut-off switching valves is switched to the transmission position by the selection switching valve, the remote controller is operated by the operation lever. Four spool stroke start point shift switches for transmitting a predetermined pressure from the pilot hydraulic power source to the pilot operating portion of the valve section of the first speed spool of the control valve when the valve is operated It is set as the structure provided with a valve. In this configuration, when each of the two-speed shut-off switching valves is switched to the transmission position by the selection switching valve, that is, when the two-pump merging series circuit system is selected, if the operation lever is operated, the first-speed spool of the control valve Because the predetermined pressure is transmitted through the spool stroke start point shift switching valve to the pilot operation portion on the non-operated side of the valve section, the stroke start point of the first-speed spool of the control valve with respect to the operation of the operation lever is It becomes slower and becomes almost the same as in the case of 1 pump 1 motor independent circuit system.

  As described above, according to the hydraulic circuit for a crane winch according to the present invention, a pilot that can hold the 2-speed spool of each control valve in a neutral position regardless of the operation of the operation lever, based on the two-pump confluence series circuit system. By providing the pressure control means, it is possible to use either the 1 pump 1 motor independent circuit system or the 2 pump merging series circuit system according to the work content, etc., thus improving the usability and contributing to the improvement of work efficiency. Can do. In addition, the pilot pressure control means controls the primary pressure or the secondary pressure of each remote control valve so that the second speed spool of each control valve can be held in the neutral position. There is no need to change, and implementation can be facilitated.

  In particular, in the invention according to claim 2, the pilot pressure control means is constituted by a plurality of two-speed shut-off switching valves provided in a pilot line of the control system of the hydraulic circuit, and the shut-off of each of the two-speed shut-off switching valves is provided. Since the second speed spool of each control valve can be reliably held at the neutral position by switching to the position, the operation reliability can be improved.

  In the invention according to claim 3, since the switching of the plurality of two-speed shut-off switching valves can be performed collectively by the selection switching valve provided in the control system of the hydraulic circuit in the same manner as this switching valve, the operation reliability and The operability can be improved.

  In the invention according to claim 4, since the capacity of each hydraulic motor is maximized at the same time when changing to the two-pump confluence series circuit system, each hydraulic motor can smoothly exhibit the maximum output, It is effective to apply to work mode.

  In the invention according to claim 5, since the capacity on the small capacity side of each hydraulic motor is changed to double at the same time when changing to the two-pump merging series circuit method, the one-pump one motor independent circuit method and the two-pump merging series The maximum rotational speed of the hydraulic motor can be made the same as that in the circuit system, and there is no sense of incongruity in operation due to the change in the circuit system, which is particularly effective when applied to the crane work mode.

  In the invention according to claim 8, when the 1-pump 1-motor independent circuit system is selected, the secondary pressure of the remote control valve operated by the operation lever is reduced by the constant ratio pressure reducing valve, and this pressure reduction is performed. Since the secondary pressure is transmitted to the pilot operating section of the valve section of the control valve 1-speed spool, the stroke change of the control valve 1-speed spool accompanying the operation of the operating lever is more gradual than in the case of the 2-pump merging series circuit system Thus, the invalid stroke area of the operation lever due to the neutral position of the second speed spool of the control valve can be reduced, and the operation characteristics of the operation lever can be improved.

  In the invention according to claim 9, when the one-pump / one-motor independent circuit system is selected, when the operation lever is operated, the spool stroke start point shift switching valve is passed through the pilot operation portion of the valve section of the first-speed spool of the control valve. Since the specified pressure is additionally transmitted, the stroke start point of the first-speed spool of the control valve in response to the operation of the operation lever can be accelerated so as to be substantially the same as in the case of the 2-pump merging series circuit system. The operating characteristics can be made better.

  Further, in the invention according to claim 10, when the two-pump merging series circuit system is selected, when the operation lever is operated, the spool is also connected to the pilot operation portion on the non-operated side of the valve section of the first speed spool of the control valve. Since a predetermined pressure is transmitted through the stroke start point shift switching valve, the stroke start point of the first-speed spool of the control valve with respect to the operation of the operation lever is delayed to be substantially the same as in the case of the one pump one motor independent circuit system. As in the case of the invention according to claim 9, the operating characteristics of the operating lever can be made better. In addition, since a general-purpose control valve can be used, an effect excellent in practicality is achieved.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments that are the best mode for carrying out the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 shows a configuration of a drive system of a hydraulic circuit for a crane winch according to a first embodiment of the present invention. Reference numeral 1 denotes a main winding winch as a first hydraulic motor for driving a main winding winch which is a first winch. 2 is a variable displacement hydraulic motor for an auxiliary winding winch as a second hydraulic motor for driving an auxiliary winding winch which is a second winch, 3 is a first variable displacement hydraulic pump, Reference numeral 4 denotes a second variable displacement hydraulic pump, and the discharge hydraulic oil from both the hydraulic pumps 3 and 4 is supplied to the main winding winch or the auxiliary winding winch via the first and second control valves 11 and 12. The operation levers 21 and 23 (see FIG. 2) are joined together and supplied to the hydraulic motors 1 and 2 for the main winding winch and the auxiliary winding winch.

  The first control valve 11 comprises a main circuit winch 1-speed spool 13 and a supplementary winch 2-speed spool 14 in a series circuit, and the second control valve 12 is also used for a main wind winch. A two-speed spool 15 and a supplementary winch first-speed spool 16 are constituted by a series circuit. The configuration of the control system of the hydraulic circuit that controls the first and second control valves 11 and 12 is shown in FIG.

  That is, in FIG. 2, reference numeral 21 denotes an operation lever for a main winding winch as a first operation lever, and a main winding as a first remote control valve according to the operation of the operation lever 21 in the winding direction or the lowering direction. The winch remote control valve 22 generates a secondary pressure, and this secondary pressure is supplied to the pilot operating portion 13a of the valve section of the first-speed spool 13 for the main winding winch of the first control valve 11 via the pilot lines 31 and 32. , 13b and the second control valve 12 are transmitted to the pilot operating portions 15a, 15b of the valve section of the main winding winch 2-speed spool 15 so that the main-winding winch first-speed spool 13 and the second-speed spool 15 stroke. It has become. Reference numeral 23 denotes an operation lever for a supplementary winch as a second operation lever, and a remote control valve for supplementary winch as a second remote control valve according to the operation of the operation lever 23 in the winding direction or the winding direction. 24 generates a secondary pressure, and the secondary pressure is supplied to the pilot operating portions 16a and 16b and the first operation portions 16a and 16b of the valve section of the first-speed spool 16 for the auxiliary winch of the second control valve 12 through the pilot lines 33 and 34. The first-speed spool 16 for the auxiliary winding winch and the second-speed spool 14 for stroke are transmitted to the pilot operating portions 14a, 14b of the valve section of the auxiliary winding winch 2-speed spool 14 of the first control valve 11.

  As shown in FIG. 11, each of the two-speed spools 14 and 15 is provided to start a stroke at a pressure higher than the hydraulic pilot pressure at which the first-speed spools 13 and 16 make a full stroke. As shown in FIG. 12, the secondary pressure characteristics of the remote control valves 22 and 24 are proportional to the operation amount of the operation levers 21 and 23 (remote control valve operation amount) and the secondary pressure. , 23 and the spool strokes of the control valves 11, 12 are as shown in FIG.

  As a feature of the present invention, the control system of the hydraulic circuit controls the secondary pressures of the remote control valves 22 and 24, thereby controlling the control valves 11 and 12 regardless of the operation of the operation levers 21 and 23. The pilot pressure control means 40 capable of holding the second speed spools 14 and 15 in the neutral position is provided. The pilot pressure control means 40 is connected to the pilot operation sections 14a, 14b, 15a, 15b of the valve sections of the second speed spools 14, 15 of the control valves 11, 12 from the respective remote control valves 22, 24. The two-speed shut-off switching valves 41, 42, 43, and 44 are provided in the two-speed spool side branch pipes 31b to 34b, respectively. The transmission position for transmitting the secondary pressure of the remote control valves 22 and 24 to the pilot operating portions 14a, 14b, 15a and 15b of the valve sections of the second speed spools 14 and 15 of the control valves 11 and 12 and the transmission of this secondary pressure are cut off. In addition, the pilot operating portions 14 a, 14 b, 15 a, 15 b are provided so as to be switchable to a shut-off position communicating with the tank 27.

  Each of the two-speed cutoff switching valves 41 to 44 is of a hydraulic control type in which switching is controlled by hydraulic pressure, and the pilot pressure control means 40 is provided with each of the two-speed cutoff switching valves 41 to 44. Is switched at once using the primary pressure of the remote control valves 22 and 24 (that is, the pressure of the pilot hydraulic source 26). This selection switching valve 45 is of an electromagnetic control type, and each of the two-speed cutoff switching valves 41 to 44 is set to the transmission position when the electromagnetic is off, and each of the two-speed cutoff switching valves 41 to 44 is set to the transmission position of the electromagnetic on. Each of 44 is switched to a blocking position.

  In the pilot pipe lines 31 to 34 communicating with the pilot operation portions of the control valves 11 and 12 from the remote control valves 22 and 24, respectively, the secondary pressures of the remote control valves 22 and 24 are respectively constant. Specific pressure reducing valves 51, 52, 53, 54 are provided, and secondary pressure switching valves 56, 57, 58, 59 are provided in the first speed spool side branch circuits 31a-34a of the pilot pipes 31-34, respectively. It has been. The secondary pressure switching valves 56 to 59 are switched in conjunction with the switching of the second speed cutoff switching valves 41 to 44 by the selection switching valve 45. When the valves 41 to 44 are switched to the transmission position, the secondary pressures of the remote control valves 22 and 24 are respectively changed to pilot operating portions 13a, 13b and 16a of the valve sections of the first speed spools 13 and 16 of the control valves 11 and 12, respectively. , 16b, and when the second speed shut-off switching valves 41-44 are switched to the shut-off position by the selection switch valve 45, the secondary pressures of the constant ratio pressure reducing valves 51-54 are respectively controlled by the control valves 11, This is transmitted to pilot operating portions 13a, 13b, 16a and 16b of the valve sections of the 12 first-speed spools 13 and 16.

  Next, the operation of the hydraulic circuit will be described. As shown in FIG. 2, when the selection switching valve 45 is in the A position, the two-speed cutoff switching valves 41 to 44 are respectively connected to the remote control valves 22 and 24, respectively. The secondary pressure is located at a transmission position for transmitting the secondary pressure to the pilot operating portions 14a, 14b, 15a, 15b of the valve sections of the second speed spools 14, 15 of the control valves 11, 12, and the secondary pressure switching valves 56-59 are respectively The secondary pressures of the remote control valves 22 and 24 are located at positions where they are transmitted to the pilot operating portions 13a, 13b, 16a and 16b of the valve sections of the first speed spools 13 and 16 of the control valves 11 and 12, respectively.

  In this case, for example, when the main winding winch operation lever 21 is operated in the winding direction or the winding direction, the main winding winch remote control valve 22 generates a secondary pressure, and this secondary pressure causes the pilot pipe lines 31 and 32 to flow. The pilot operation parts 13a and 13b of the valve section of the first speed spool 13 for the main winding winch of the first control valve 11 and the pilot operation part of the valve section of the second speed spool 15 for the main winding winch of the second control valve 12 15a and 15b are transmitted to the main winding winch first speed spool 13 and second speed spool 15. In this case, as shown in FIG. 12, the relationship between the operation amount of the operation lever 21 (remote control valve operation amount) and the spool stroke is as follows. First, the first speed spool 13 starts the stroke and shifts to the full stroke (the first stroke). Speed) and then the second speed spool 15 starts a stroke and shifts to a full stroke (second speed). Then, at the first speed, only the discharge hydraulic oil of the first hydraulic pump 3 is supplied to the hydraulic motor 1 for the main winding winch through the first speed spool 13 for the main winding winch of the first control valve 11, and the second At high speed, the hydraulic oil discharged from the first and second hydraulic pumps 3 and 4 is discharged from the hydraulic motor 1 for the main winding winch through the main winding winch first speed spool 13 and the second speed spool 15 of the control valves 11 and 12. The so-called two-pump merging series circuit system is realized.

  On the other hand, when the selection switching valve 45 is switched to the low position, each of the second-speed cutoff switching valves 41 to 44 transmits the secondary pressure of the selection switching valve 45 to the pilot operation unit, thereby causing the remote control valve 22, 24 is blocked from being transmitted to the pilot operating portions 14a, 14b, 15a, 15b of the valve sections of the second speed spools 14, 15 of the control valves 11, 12, and the pilot operating portions 14a, 14b, 15a, 15b is switched to the shut-off position communicating with the tank 27. As a result, even when the operation levers 21 and 23 are largely operated, the secondary pressure of the remote control valves 22 and 24 is controlled by the pilot operation portions 14a, 14b, 15a and 15b of the valve sections of the second speed spools 14 and 15 of the control valves 11 and 12. The second-speed spools 14 and 15 of the control valves 11 and 12 are held in the neutral position without stroke, so that the hydraulic motor 1 for the main winding winch is the first hydraulic pump 3. Thus, the hydraulic motor 2 for the auxiliary winding winch is supplied with the discharge pressure oil of the second hydraulic pump 4 independently of each other, and a one-pump / one-motor independent circuit system is realized.

  As described above, the two-pump merging series circuit method and the one-pump one-motor independent circuit method can be selectively realized by switching the selection switching valve 45, and can be selectively used according to the work contents. This can contribute to improvement of work efficiency.

  Further, when the selection switching valve 45 is switched to the low position, that is, when the 1-pump 1-motor independent circuit system is selected, simultaneously with the switching of each of the above-described 2-speed cutoff switching valves 41 to 44 to the cutoff position, Each of the secondary pressure switching valves 56 to 59 transmits the secondary pressure of the constant ratio pressure reducing valves 51 to 54 to the control valve 11, by transmitting the pressure of the pilot hydraulic pressure source 26 through the selection switching valve 45 to the pilot operating unit. The first 1-speed spools 13 and 16 are switched to positions where they are transmitted to the pilot operating portions 13a, 13b, 16a and 16b of the valve section. Thus, when the operation levers 21 and 23 are operated, the secondary pressure of the remote control valves 22 and 24 is directly applied to the pilot operation portions 13a, 13b, 16a and 16b of the valve sections of the first speed spools 13 and 16 of the control valves 11 and 12. Instead of transmission, the secondary pressure of the constant ratio pressure reducing valves 51 to 54 obtained by reducing the secondary pressure of the remote control valves 22 and 24 by the constant ratio pressure reducing valves 51 to 54 is changed to the first speed spool 13 of the control valves 11, 12. This is transmitted to the pilot operating portions 13a, 13b, 16a and 16b of the 16 valve sections. In the present embodiment, since the constant ratio of the constant ratio pressure reducing valves 51 to 54 is ½, the first speed spools 13 and 16 of the control valves 11 and 12 with respect to the operation amounts of the remote control valves 22 and 24 by the operation levers 21 and 23. The relationship of the pilot pressure transmitted to the pilot operating portions 13a, 13b, 16a, and 16b of the valve section of FIG. 14 is shown by the solid line A in FIG. As shown.

  As a result, the relationship between the operation amounts of the remote control valves 22 and 24 by the operation levers 21 and 23 and the strokes of the first speed spools 13 and 16 of the control valves 11 and 12 is as shown by a dotted line B in FIG. Compared with the case indicated by the solid line A in FIG. 15 when the pressure reducing valves 51 to 54 are not provided, the stroke change of the first speed spools 13 and 16 of the control valves 11 and 12 accompanying the operation of the operation levers 21 and 23 becomes gentle. Therefore, the invalid stroke area of the operation levers 21 and 23 by holding the neutral position of the second speed spools 14 and 15 of the control valves 11 and 12 can be reduced, and the operation characteristics of the operation levers 21 and 23 are improved. be able to.

(Second Embodiment)
3 and 4 show the hydraulic circuit of the crane winch according to the second embodiment of the present invention, FIG. 3 shows the configuration of the drive system of the hydraulic circuit, and FIG. 4 shows the configuration of the control system of the hydraulic circuit. Indicates. In the case of the second embodiment, the basic configuration of the hydraulic circuit is the same as in the case of the first embodiment, and the same members / parts are denoted by the same reference numerals and the description thereof is omitted. Only matters different from the case of the embodiment will be described below.

  That is, in the drive system of the hydraulic circuit shown in FIG. 3, the valve sections of the first speed spools 13 and 16 of the control valves 11 and 12 are respectively connected to the pilot operating portions 13a, 13b, 13c, 13d, 16a, 16b, Two strokes 16c and 16d are provided, and the stroke of the first speed spools 13 and 16 is determined by the sum of pilot pressures acting on the operation portions 13a and 13c, 13b and 13d, 16a and 16c, or 16b and 16d, respectively. Is provided. The relationship between the total pilot pressure and the strokes of the first-speed spools 13 and 16 is the same as that in the first embodiment, as shown in FIG.

  On the other hand, in the control system of the hydraulic circuit shown in FIG. 4, when the selection switching valve 45 is switched to the low position (that is, when the 1 pump 1 motor independent circuit system is selected), the transmission is transmitted through this selection switching valve 45. The pressure reducing valve 60 for reducing the hydraulic pressure of the pilot hydraulic power source 26 to a predetermined pressure, and the secondary pressure of the pressure reducing valve 60 in each direction in the valve sections of the first speed spools 13 and 16 of the control valves 11 and 12, respectively. Are provided with four spool stroke start point shifting switching valves 61, 62, 63, 64 for transmission to one of the pilot operating portions 13c, 13d, 16c, 16d.

  In the present embodiment, the pressure reducing valve 60 is set so that its secondary pressure is a pressure value corresponding to ΔPi in FIG. The spool stroke start point shift switching valves 61 to 64 are switched by transmitting the pressure downstream of the secondary pressure switching valves 56 to 59 of the pilot pipes 31 to 34 to the pilot operating section. When the selection switching valve 45 is switched to the low position and the remote control valves 22 and 24 are operated by the operation levers 21 and 23, the secondary pressure of the pressure reducing valve 60 is set to each control valve 11, Twelve first-speed spools 13 and 16 are provided so as to be transmitted to one pilot operation portion 13c, 13d, 16c and 16d in each direction in the valve section.

  Next, the operation of the hydraulic circuit will be described. When the selection switching valve 45 is in the A position, it is exactly the same as in the first embodiment, and the two-pump merging series circuit system is realized. . In this case, when the remote control valves 22 and 24 are operated by the operation levers 21 and 23, the secondary pressure is applied to the pilot operation portions of the spool stroke start point shift switching valves 61 to 64 via the pilot pipe lines 31 to 34. Then, the switching valves 61 to 64 perform switching operation. However, since the primary side of the pressure reducing valve 60 communicates with the tank 27, the first speed spools 13 and 13 of the control valves 11 and 12 pass through the switching valves 61 to 64. No pressure acts on the sixteen pilot operating portions 13c, 13d, 16c, and 16d.

  On the other hand, when the selection switching valve 45 is switched to the low position, each of the two-speed cutoff switching valves 41 to 44 is switched to the cutoff position as in the case of the first embodiment. The next pressure is not transmitted to the pilot operating portions 14a, 14b, 15a, 15b of the valve sections of the second speed spools 14, 15 of the control valves 11, 12, and the control valves 11, 12 are operated regardless of the operation of the operating levers 21, 23. Since the two-speed spools 14 and 15 are held in the neutral position without a stroke, an independent circuit system for one pump and one motor is realized.

  At the same time, each of the secondary pressure switching valves 56 to 59 supplies the secondary pressure of the constant ratio reducing valves 51 to 54 to the pilot operating portions 13a, 13b, 16a of the valve sections of the first speed spools 13 and 16 of the control valves 11 and 12, respectively. The position is transmitted to 16b. Further, since the pressure of the pilot hydraulic pressure source 26 is transmitted to the primary side of the pressure reducing valve 60 through the selective switching valve 45, the secondary pressure ΔPi is generated in the secondary side pipe P. When the remote control valves 22 and 24 are operated by the operating levers 21 and 23 in this state, the secondary pressure of the constant ratio pressure reducing valves 51 to 54 is pilot operated on the valve section of the first speed spools 13 and 16 of the control valves 11 and 12. While acting on the parts 13a, 13b, 16a, 16b, it also acts on the pilot operating portions of the spool stroke start point shifting switching valves 61-64, so that the switching valves 61-64 perform switching operations, respectively. The secondary pressure ΔPi of the valve 60 also acts on the pilot operating portions 13c, 13d, 16c and 16d of the valve sections of the first speed spools 13 and 16 of the control valves 11 and 12.

  As a result, when the remote control valves 22 and 24 are operated, the relationship between the operation amount of the remote control valves 22 and 24 and the pilot pressure (total value) acting on the first speed spools 13 and 16 is indicated by a one-dot chain line C in FIG. Thus, the remote control valve operation amount corresponding to the pilot pressure Pia (see FIG. 11) at which the first-speed spools 13 and 16 start the stroke becomes the same in S1. Therefore, the relationship between the operation amount of the remote control valves 22 and 24 and the stroke of the first speed spools 13 and 16 of the control valves 11 and 12 is as shown by a one-dot chain line C in FIG.

  In the first embodiment, the relationship between the strokes of the first-speed spools 13 and 16 of the control valves 11 and 12 with respect to the operation amounts of the remote control valves 22 and 24 when the 1-pump 1-motor independent circuit method is selected is the broken line in FIG. The operation amount of the remote control valves 22 and 24 corresponding to the start point of the spool stroke is larger by ΔS than that when the two-pump merging series circuit method is selected (solid line A in FIG. 15). However, in the second embodiment, the operation amount of the remote control valves 22 and 24 and the stroke relationship of the first speed spools 13 and 16 of the control valves 11 and 12 can be corrected by ΔS, so that one pump and one motor independent circuit system The stroke start point of the first speed spools 13 and 16 with respect to the operation amount of the remote control valves 22 and 24 is S1 ( (See FIG. 14). For this reason, as in the case of the first embodiment, coupled with the fact that the invalid stroke area of the operation levers 21, 23 can be reduced by holding the neutral positions of the second speed spools 14, 15 of the control valves 11, 12. The operating characteristics of the operating levers 21 and 23 can be made very good.

(Third embodiment)
FIG. 5 shows the configuration of the control system of the hydraulic circuit of the winch for crane according to the third embodiment of the present invention. The configuration of the drive system of the hydraulic circuit is the same as that of the first embodiment, and in the following description, the reference numerals are also referred to when referring to FIG. Further, the basic configuration of the control system of the hydraulic circuit is the same as that of the first embodiment, and the same members / parts are denoted by the same reference numerals, and the description thereof is omitted. Only matters different from the case will be described below.

  That is, in the control system of the hydraulic circuit, the pressure reducing valve 70 that reduces the hydraulic pressure of the pilot hydraulic source 26 to a predetermined pressure as the primary pressure, and the first-speed spool side branch circuits 31a to 34a of the pilot pipelines 31 to 34, respectively. Four spool stroke start point shift switching valves 71, 72, 73, 74 provided downstream of the next pressure switching valves 56-59, respectively, and four switches for controlling the switching operation of the switching valves 71-74. Control switching valves 76, 77, 78, and 79 are further provided.

  In the present embodiment, the pressure reducing valve 70 is set so that its secondary pressure is a pressure value corresponding to ΔPi in FIG. Each of the spool stroke start point shift switching valves 71 to 74 normally applies the pressure transmitted through the secondary pressure switching valves 56 to 59 to the valve sections of the first speed spools 13 and 16 of the control valves 11 and 12 as they are. The pilot pressure is transmitted to the pilot operating portions 13a, 13b, 16a, 16b, and the secondary pressure of the pressure reducing valve 70 is controlled by switching operation when a predetermined pressure is applied to the pilot operating portion through the switching control switching valves 76-79. The first and second speed spools 13 and 16 of the valves 11 and 12 are provided so as to transmit to the pilot operating portions 13a, 13b, 16a and 16b of the valve section. The switching control switching valves 76 to 79 are selected switching valves. 45 is in the A position and each of the two-speed cutoff switching valves 41 to 44 is switched to the transmission position and the operation lever 21 23, when the remote control valves 22 and 24 are operated, the secondary pressure of the remote control valves 22 and 24 is provided from the pilot line on the operating side of the operating levers 21 and 23 to the pilot line on the non-operating side. The spool stroke start point shift switching valves 71 to 74 are provided so as to be transmitted to the pilot operating portion. Therefore, the spool stroke start point shifting switching valves 71 to 74 are controlled by the selection switching valve 45 when the two-speed shut-off switching valves 41 to 44 are switched to the transmission position and the operation levers 21 and 23 are remote control valves. When the valves 22 and 23 are operated, the secondary pressure of the pressure reducing valve 70 is transmitted to the pilot operating portion of the valve section of the first speed spools 13 and 16 of the control valves 11 and 12 which is not operated. Yes.

  Further, the secondary pressure characteristics of the remote control valves 22 and 24 are as shown by a solid line A in FIG. 16, and compared with the secondary pressure characteristics shown by a solid line A in FIG. 14 in the case of the first embodiment. , ΔPi, and a characteristic shifted upward.

  Next, the operation of the hydraulic circuit will be described. When the selection switching valve 45 is in the A position, each of the second-speed cutoff switching valves 41 to 44 controls the secondary pressure of the remote control valves 22 and 24 respectively. , 12 at the transmission position for transmitting to the pilot operating portions 14a, 14b, 15a, 15b of the valve sections of the two-speed spools 14, 15, the secondary pressure switching valves 56-59 are respectively connected to the remote control valves 22, 24, respectively. It is located at a position where the secondary pressure is transmitted to the pilot operating portions 13a, 13b, 16a, 16b of the valve sections of the first speed spools 13, 16 of the control valves 11, 12. Further, each of the switching control switching valves 76 to 79 applies the secondary pressure of the remote control valves 22 and 24 from the pilot line on the side where the operation levers 21 and 23 are operated when the remote control valves 22 and 24 are operated. It is located at a position where it is transmitted to the pilot operating portion of the spool stroke start point shifting switching valves 71 to 74 provided in the pilot line on the non-operated side.

  In this case, when the remote control valves 22 and 24 are operated by the operation levers 21 and 23, the secondary pressure of the remote control valves 22 and 24 is directly piloted on the operated side of the valve section of the first speed spools 13 and 16 of the control valves 11 and 12. The first speed spools 13, 16 and the second speed spool are transmitted to the pilot operation sections 14a, 14b, 15a and 15b on the operated side of the valve sections of the operation sections 13a, 13b, 16a and 16b and the second speed spools 14 and 15. 14, 15 strokes in the operation direction of the operation levers 21 and 23 and according to the operation amount, and a two-pump confluence series circuit system is realized.

  At the same time, the secondary pressures of the remote control valves 22 and 24 are also applied to the pilot operation portions of the spool stroke start point shift switching valves 71 to 74 provided in the pilot pipes 31 to 34 on the side where the operation levers 21 and 23 are not operated. Is transmitted from the pilot pipelines 31 to 34 on the operated side of the operation levers 21 and 23 through the switching valves 76 to 79 for switching control, and the switching valves 71 to 74 for shifting the spool stroke start point perform switching operation. The secondary pressure of the pressure reducing valve 70 is transmitted to the pilot operating portions 13a, 13b, 16a and 16b on the side where the valve sections of the first speed spools 13 and 16 of the control valves 11 and 12 are not operated. The first-speed spools 13 and 16 of the control valves 11 and 12 have their stroke amounts determined by the pressure difference between the pilot operating portions 13a, 13b, 16a and 16b on both sides. The relationship between the pilot pressures (differential pressures) acting on 13 and 16 is as shown by a two-dot chain line C in FIG.

  On the other hand, when the selection switching valve 45 is switched to the low position, each of the two-speed cutoff switching valves 41 to 44 is switched to the cutoff position, as in the first embodiment, and the remote control valves 22, 24 The secondary pressure is not transmitted to the pilot operating portions 14a, 14b, 15a, 15b of the valve sections of the second speed spools 14, 15 of the control valves 11, 12, and the control valves 11, 23 are operated regardless of the operation of the operating levers 21, 23. Since the 12 second-speed spools 14 and 15 are held in the neutral position without a stroke, a 1-pump 1-motor independent circuit system is realized.

  At the same time, each of the secondary pressure switching valves 56 to 59 applies the secondary pressure of the constant ratio reducing valves 51 to 54 to the pilot operating portions 13a, 13b, 16a of the valve sections of the first speed spools 13, 16 of the control valves 11, 12. The pilot pressure transmitted to the pilot operating portions 13a, 13b, 16a and 16b of the valve section of the first speed spools 13 and 16 of the control valves 11 and 12 with respect to the operation amount of the remote control valves 22 and 24 is switched to the position to be transmitted to 16b. The relationship is as shown by a broken line B in FIG. As can be seen from FIG. 16, the operation amounts of the remote control valves 22 and 24 corresponding to the pilot pressure Pia at which the first-speed spools 13 and 16 start the stroke in both the 1-pump 1-motor independent circuit system and the 2-pump merging series circuit system. Therefore, the operation characteristics of the operation levers 21 and 23 can be made very good. In addition, as in the case of the second embodiment, it is necessary to use special control valves 11 and 12 in which the valve sections of the first-speed spools 13 and 16 have two pilot operation portions 13a to 13d and 16a to 16d in each direction. Since the same effect can be exhibited by using the general-purpose control valves 11 and 12, implementation can be facilitated accordingly.

  When the selection switching valve 45 is switched to the low position, each switching control switching valve 76 to 79 transmits the pressure of the pilot hydraulic power source 26 to the pilot operating portion through the selection switching valve 45 and switches from the position shown in the figure. In order to operate, the pilot operating portion of the spool stroke start point shifting switching valves 71 to 74 communicates with the tank 27, and the switching valves 71 to 74 are fixed at the positions shown in the drawing. Therefore, the secondary pressure of the pressure reducing valve 70 is not transmitted to the pilot operating portions 13a, 13b, 16a, 16b on the non-operated side of the valve sections of the first speed spools 13, 16 of the control valves 11, 12.

  In FIG. 16, E is a characteristic line showing the relationship between the operation amount of the remote control valve and the stroke of the first speed spool in this embodiment, and F is the operation amount of the remote control valve and the stroke of the first speed spool in the conventional example. It is a characteristic line which shows the relationship.

(Fourth embodiment)
FIG. 6 shows a modification of the control system of the hydraulic circuit of the crane winch according to the third embodiment as the fourth embodiment of the present invention. In the case of the fourth embodiment, four spool stroke start point shift switches provided downstream of the secondary pressure switching valves 56 to 59 of the first speed spool side branch circuits 31a to 34a of the pilot pipes 31 to 34, respectively. The configuration for controlling the switching operation of the valves 71, 72, 73, 74 is different.

  That is, the pilot operating portions of the spool stroke start point shifting switching valves 71 to 74 operate the secondary pressure of the remote control valves 22 and 24 when the remote control valves 22 and 24 are operated by the operation levers 21 and 23. The spool stroke start point shift switching valve 71 provided in the pilot line on the non-operated side from the pilot lines 31 to 34 on the operated side of the levers 21 and 23 through the pilot lines 81, 82, 83 and 84. It is provided so that it may transmit to pilot operation part of -74. Further, a pilot switching valve 85 is provided on the primary side of the pressure reducing valve 70 that reduces the pressure to a predetermined pressure (ΔPi in FIG. 14 in this embodiment) using the hydraulic pressure of the pilot hydraulic power source 26 as a primary pressure. The valve 85 transmits the pressure of the pilot hydraulic pressure source 26 to the pressure reducing valve 70 side when the selection switching valve 45 is in the A position, and cuts off the transmission when the selection switching valve 45 is switched to the B position and the pressure reducing valve. The primary side of 70 communicates with the tank 27.

  Accordingly, in each of the spool stroke start point shifting switching valves 71 to 74, the selection switching valve 45 is in the A position and each of the second speed cutoff switching valves 41 to 44 is in the transmission position, as in the third embodiment. When the remote control valves 22 and 23 are operated by the operation levers 21 and 23, the secondary pressure of the pressure reducing valve 70 is applied to the valve sections of the first speed spools 13 and 16 of the control valves 11 and 12, respectively. This is transmitted to the pilot operating sections 13a, 13b, 16a, and 16b on the side that is not operated. As a result, this embodiment also operates in the same manner as in the third embodiment, and of course has the same effects.

(Fifth embodiment)
FIG. 7 shows a block configuration of an electric control system of a hydraulic circuit of a winch for a crane according to a fifth embodiment of the present invention. The basic structure of the hydraulic circuit of the crane winch is the same as that of the first embodiment, and in the following description, when referring to FIGS. Also quote the sign.

  In FIG. 7, reference numeral 90 denotes a motor tilt proportional valve that changes the tilt angle of the hydraulic motors 1 and 2 (see FIG. 1) for the main winding winch and the auxiliary winding winch, and 91 denotes the motor tilt proportional valve 90. A controller that outputs a control command. Among the control commands of the controller 91, a command for changing the capacity of the hydraulic motors 1 and 2 to a maximum is provided between the solenoid portion of the selection switching valve 45 and the battery power source 92. When the switch 93 cuts off the power to the solenoid, that is, when the selection switching valve 45 is switched from the low position to the a position, and each of the second speed cutoff switching valves 41 to 44 is switched from the cutoff position to the transmission position. Output.

  In the fifth embodiment, the same effects as those of the first embodiment can be obtained, and when the selection switching valve 45 is switched to the A position by the switch 93, that is, a two-pump merging series circuit. At the same time, the controller 91 outputs a maximum capacity change command from the controller 91 to the motor tilt proportional valve 90, and the motor tilt proportional valve 90 allows the capacities of the hydraulic motors 1 and 2 for the main winding winch and the auxiliary winding winch to be increased. Since it is changed to the maximum, each of the hydraulic motors 1 and 2 can smoothly exhibit the maximum output, and is particularly effective when applied to the bucket work mode.

(Other embodiments)
The present invention is not limited to the first to fifth embodiments, but includes various other forms. For example, in each of the above embodiments, the pilot pressure control means 40 that can hold the second speed spools 14 and 15 of the control valves 11 and 12 in the neutral position regardless of the operation of the operation levers 21 and 23 is provided in the pilot pipe lines 31 to 34. Although the four-speed shut-off switching valves 41, 42, 43, 44 provided on the two-speed spool side branch pipes 31b to 34b, respectively, the present invention is configured by the two-speed shut-off switching valves 41, 42. , 43, 44, four electromagnetic proportional pressure reducing valves 101, 102, 103, 104 are provided in the two-speed spool side branch pipes 31b-34b of the pilot pipe lines 31-34, respectively, as shown in FIG. As shown in FIG. 1, one electromagnetic proportional pressure reducing valve 106 is provided in the primary pilot line 107 of the remote control valves 22 and 24, and these electromagnetic proportional pressure reducing valves 101 to 104 or As a result, the secondary pressure of the remote control valves 22 and 24 is reduced to a pressure lower than the pressure value at which the second speed spools 14 and 15 of the control valves 11 and 12 start the stroke, thereby bringing the second speed spools 14 and 15 to the neutral position. You may comprise so that it may hold | maintain.

  As a modification of the fifth embodiment, as shown in FIG. 10, the selector valve 45 is switched from the low position to the a position by the switch 93, and the two-speed cutoff switching valves 41 to 44 are moved from the cutoff position. When switching to the transmission position, a switching signal from the switch 93 is taken into the controller 91 and the controller 91 instructs the motor tilt proportional valve 90 to double the capacity on the small capacity side of each hydraulic motor 1, 2. You may comprise so that a signal may be output. When only one of the hydraulic motors 1 and 2 for the main winding winch and the auxiliary winding winch is operated in the two-pump confluence series circuit system, the maximum rotation speed is the hydraulic pressure in the one-pump / one-motor independent circuit system. Although the maximum rotational speed of the motors 1 and 2 is doubled, in the case of this modification, each of the two-speed shut-off switching valves 41 to 44 is switched from the shut-off position to the transmission position and changed to the two-pump confluence series circuit At the same time, the capacity on the small capacity side of each of the hydraulic motors 1 and 2 is changed to twice, and the maximum rotational speed of each of the hydraulic motors 1 and 2 is reduced to ½. For this reason, the maximum rotational speed of the hydraulic motor can be made the same in the 1-pump 1-motor independent circuit system and the 2-pump merging series circuit system, and there is no sense of incongruity in operation due to the change in the circuit system. It is effective to apply to the crane working mode.

  Further, in each of the above embodiments, the four two-speed shut-off switching valves 41 to 44 constituting the pilot pressure control means 40 are of the hydraulic control type, and the switching operation is controlled by the single selection switching valve 45. Of course, in the present invention, each of the two-side cutoff switching valves may be changed to an electromagnetic control type.

It is a block diagram of the drive system of the hydraulic circuit of the winch for cranes concerning the 1st Embodiment of this invention. It is the block diagram of a control system similarly. FIG. 3 is a view corresponding to FIG. 1 showing a second embodiment. Similarly, FIG. FIG. 9 is a view corresponding to FIG. 2 showing a third embodiment. FIG. 9 is a view corresponding to FIG. 2 and showing a fourth embodiment. It is a block block diagram of the electric control system of the hydraulic circuit of the winch for cranes concerning 5th Embodiment. FIG. 3 is a view corresponding to FIG. 2 showing another embodiment. FIG. 3 is a view corresponding to FIG. 2 showing another embodiment. FIG. 10 is a view corresponding to FIG. 7 showing another embodiment as a modification of the fifth embodiment. It is a spool stroke characteristic view of a control valve. It is a characteristic view which shows the relationship between the operation amount of a remote control valve, and secondary pressure. It is a characteristic view which shows the relationship between the operation amount of a remote control valve, and a spool stroke. It is a characteristic view which shows the relationship between the operation amount of a remote control valve, and pilot pressure. It is a characteristic view which shows the relationship between the operation amount of a remote control valve, and a 1st speed spool stroke. It is a characteristic view which shows the relationship between the operation amount of a remote control valve, pilot pressure, and 1st speed spool stroke. It is a figure equivalent to FIG. 1 which shows a prior art example. It is a figure equivalent to FIG. 1 which shows another prior art example. Similarly, FIG.

Explanation of symbols

1 Hydraulic motor for primary winding winch (first hydraulic motor)
2 Hydraulic motor for auxiliary winding winch (second hydraulic motor)
DESCRIPTION OF SYMBOLS 3 1st hydraulic pump 4 2nd hydraulic pump 11 1st control valve 12 2nd control valve 13 1 speed spool for main winding winches (1 speed spool for 1st winches)
14 2-speed spool for auxiliary winding winch (2-speed spool for second winch)
15 2-speed spool for main winding winch (2-speed spool for 1st winch)
16 1-speed spool for auxiliary winch (1-speed spool for 2nd winch)
13a, 13b, 14a, 14b, 15a, 15b, 16a, 16b Pilot operating portion 21 Main winding winch operating lever (first operating lever)
22 Remote control valve for main winding winch (first remote control valve)
23 Operation lever for auxiliary winding winch (second operation lever)
24 Remote control valve for auxiliary winding winch (second remote control valve)
26 Pilot hydraulic power source 27 Tank 31, 32, 33, 34 Pilot conduit 40 Pilot pressure control means 41, 42, 43, 44 2-speed shut-off switching valve 45 Selection switching valve 51, 52, 53, 54 Constant ratio pressure reducing valve 56 , 57, 58, 59 Secondary pressure switching valve 60, 70 Pressure reducing valve 61, 62, 63, 64, 71, 72, 73, 74 Spool stroke start point shifting switching valve 76, 77, 78, 79 Switching control switching Valves 101, 102, 103, 104, 106 Proportional pressure reducing valve

Claims (10)

The first hydraulic motor for driving the first winch, the second hydraulic motor for driving the second winch, the first and second hydraulic pumps, and the discharge pressure oil of both hydraulic pumps for operating the operation lever And first and second control valves that are joined together and supplied to the first and second hydraulic motors, respectively, and the first control valve is operated by a first operating lever. The first winch 1-speed spool that strokes at the secondary pressure of the second and the second winch 2-speed spool that strokes at the secondary pressure of the second remote control valve operated by the second operating lever are configured in a series circuit. The second control valve includes a second winch spool for the first winch that strokes with the secondary pressure of the first remote control valve operated by the first operating lever, and a second operating lever. The first winch spool for the second winch that strokes with the secondary pressure of the second remote control valve operated in a series is constituted by a series circuit, and each of the second speed spools is a hydraulic pilot pressure at which the first speed spool makes a full stroke. In the hydraulic circuit of the crane winch, which is configured to start the stroke at a higher pressure,
Pilot pressure control means capable of holding the second speed spool of each control valve in a neutral position regardless of operation of the operation lever by controlling the primary pressure or the secondary pressure of each remote control valve is provided. Hydraulic circuit for winch for crane.   The pilot pressure control means has a two-speed shut-off switching valve provided in a pilot line communicating from each remote control valve to a pilot operating portion of a valve section of a two-speed spool of the control valve. The switching valve for the remote control valve transmits the secondary pressure to the pilot operating part of the valve section of the second speed spool of the control valve, and interrupts the transmission of the secondary pressure and the pilot operating part to the tank. The hydraulic circuit of the winch for cranes of Claim 1 provided so that switching to a position was possible.   Each of the two-speed shut-off switching valves is controlled by hydraulic pressure, and the pilot pressure control means collectively switches the two-speed shut-off switching valves using a pilot pressure source. The hydraulic circuit of the winch for cranes of Claim 2 which has a selection switching valve.   The first and second hydraulic motors are both of a variable displacement type, and are configured to maximize the capacity of each hydraulic motor at the same time when switching each of the two-speed cutoff switching valves from the cutoff position to the transmission position. The hydraulic circuit of the winch for cranes of Claim 2 or 3 currently provided.   Both the first and second hydraulic motors are of the variable displacement type, and at the same time when each of the two-speed shut-off switching valves is switched from the shut-off position to the transmission position, the capacity on the small capacity side of each hydraulic motor is doubled. The hydraulic circuit of the winch for cranes of Claim 2 or 3 comprised so that it may become.   The pilot pressure control means has an electromagnetic proportional pressure reducing valve provided in a pilot line communicating from each remote control valve to a pilot operating portion of the valve section of the second speed spool of the control valve. The crane winch according to claim 1, wherein the second pressure of the remote control valve is reduced to a pressure lower than a pressure value at which the second speed spool starts a stroke to hold the second speed spool in a neutral position. Hydraulic circuit.   The pilot pressure control means has at least one electromagnetic proportional pressure reducing valve provided in a pilot line communicating from the pilot hydraulic power source to the remote control valve. The electromagnetic proportional pressure reducing valve reduces the primary pressure of the remote control valve. 2. The hydraulic circuit for a winch for a crane according to claim 1, wherein the second pressure is reduced to a pressure lower than a pressure value at which the second speed spool starts a stroke to hold the second speed spool in a neutral position. . Four constant pressure reducing valves for reducing the secondary pressure of each of the remote control valves, respectively;
When each of the two-speed shut-off switching valves is switched to the transmission position by the selection switching valve, the secondary pressure of each remote control valve is transmitted to the pilot operating portion of the valve section of the first-speed spool of the control valve. In order to transmit the secondary pressure of each of the constant ratio pressure reducing valves to the pilot operating portion of the valve section of the first speed spool of the control valve when each of the second speed cutoff switching valves is switched to the cutoff position by the switching valve. The hydraulic circuit for a winch for a crane according to claim 3, comprising four secondary pressure switching valves. The valve section of the first-speed spool of the control valve has two pilot operation portions in each direction, and is provided so that the spool stroke is determined by the sum of the pilot pressures acting on both operation portions,
When each of the two-speed shut-off switching valves is switched to the shut-off position by the selection switching valve and when the remote control valve is operated by the operation lever, a predetermined pressure is applied from the pilot hydraulic power source to the first-speed spool of the control valve. 9. The hydraulic circuit for a crane winch according to claim 8, further comprising four spool stroke start point shift switching valves for transmitting to one pilot operating portion in each direction in the valve section.   When each of the two-speed cutoff switching valves is switched to the transmission position by the selection switching valve and when the remote control valve is operated by the operation lever, a predetermined pressure is applied from the pilot hydraulic power source to the first-speed spool of the control valve. 9. The hydraulic circuit for a crane winch according to claim 8, further comprising four spool stroke start point shifting switching valves for transmission to a pilot operating portion on the non-operated side of the valve section.