JP4797916B2 - Control device for variable displacement hydraulic motor - Google Patents

Description

  The present invention relates to a control device for a variable displacement hydraulic motor that is used for a winch or the like of a construction machine such as a crane and changes a rotational speed and the like together with a capacity. The present invention relates to a control device for a variable displacement hydraulic motor that can prevent occurrence of hunting and hunting.

  As a control device for a variable displacement hydraulic motor used for a winch of a construction machine such as a crane and capable of changing a rotation speed as well as a capacity of the motor, for example, a configuration as described later is used. Is known. Hereinafter, typical examples of the control apparatus for the variable displacement hydraulic motor according to the conventional example will be introduced.

  A control apparatus for a variable displacement hydraulic motor according to Conventional Example 1 will be described with reference to the attached drawings. FIG. 3 is a hydraulic circuit diagram of a control device that performs capacity control and overload prevention control of a variable displacement hydraulic motor, and FIG. 4 is a diagram showing a relationship between input pilot pressure and motor capacity by the control device of the variable displacement hydraulic motor. It is. FIG. 5 is a diagram showing the relationship between the motor driving pressure and the motor capacity of the variable displacement hydraulic motor, and FIG. 6 is a diagram showing the relationship between the motor output torque and the motor rotation speed of the variable displacement hydraulic motor.

  Reference numeral 51 shown in FIG. 3 is a variable displacement hydraulic motor, and reference numeral 52 is a servo-type displacement control mechanism for controlling the motor displacement of the variable displacement hydraulic motor 51. The capacity control mechanism 52 includes a hydraulic pilot type spool valve (servo valve) 53 controlled by a pilot pressure Pi from a means (for example, a remote control valve) (not shown), and a motor driving pressure Pa via the spool valve 53. , Pb and the hydraulic piston 54 that drives the tilting mechanism of the variable displacement hydraulic motor 51. The hydraulic piston 54 operates in response to the pilot pressure Pi, and the variable displacement hydraulic motor The motor capacity of 51 is controlled. The relationship between the pilot pressure Pi when controlling the motor capacity of the variable displacement hydraulic motor 51 and the motor capacity is as shown in FIG. That is, the motor capacity changes from the maximum value qb to the minimum value qa in accordance with the pilot pressure between the pilot pressures Pia to Pib. In the drawing, Pix is a value between pilot pressures Pia to Pib at which the motor capacity changes, and qx is a motor capacity at the pilot pressure Pix.

  Based on the above configuration, a high pressure selection valve (shuttle valve) that selects a pressure on the high pressure side of the pressure Pa of the winding side flow channel 57 and the pressure Pb of the lowering flow channel 58, that is, the motor driving pressures Pa and Pb. Between 55 and the spool valve 53, a pressure compensation valve 56 is provided for constant pressure control. As shown in FIG. 5, the pressure compensation valve 56 has a small motor capacity qa when the motor driving pressures Pa and Pb reach a preset set pressure Ps as a pressure at which the overload prevention action should be started. Is switched to a large capacity qb, and the motor is operated with high torque and low rotation. With this configuration, constant horsepower control as shown in FIG. 6 is performed by pressure constant control at the set pressure Ps, and overloading of the variable displacement hydraulic motor 51 is prevented (see, for example, Patent Document 1).

  A control apparatus for a variable displacement hydraulic motor according to Conventional Example 2 will be described with reference to FIG. 7 of a hydraulic circuit diagram in which the control apparatus for the variable displacement hydraulic motor is simplified. In the overload prevention control of the control device according to Conventional Example 2, a pressure compensation valve that operates at a differential pressure (Pa−Pb) = Ps between the motor drive pressures Pa and Pb is provided. Hereinafter, it demonstrates in detail based on FIG. That is, the variable displacement hydraulic motor 61 is a swash plate piston motor. When pressure oil is supplied to the hydraulic flow path 63 from a hydraulic pump (not shown), the variable displacement hydraulic motor 61 rotates in a direction to wind up the winch. . Further, when the variable displacement hydraulic motor 61 is rotated in the direction in which the winch is wound, the pressure oil is supplied from the hydraulic passage 64 to the variable displacement hydraulic motor 61. The variable displacement hydraulic motor 61 can change the motor capacity by changing the tilt angle of the swash plate. The tilt angle of the swash plate is controlled by the tilt angle control means 65. It has become.

The tilt angle control means 65 includes a first stepped piston 66 connected to a swash plate, the large diameter portion 69 of the first stepped piston 66 is disposed in the first piston chamber 67, and the small diameter portion 70 is a first diameter portion. Arranged in the two-piston chamber 68. When the hydraulic flow path 63 and the first piston chamber 67 are connected by the control device 62 described later, the pressure oil of the supply pressure Pa acts on the large diameter portion 69 of the first stepped piston 66, and the first stepped piston. 66 moves to one side (left side in FIG. 7). As a result, the tilt angle of the swash plate of the variable displacement hydraulic motor 61 becomes small, and the motor capacity decreases. When the hydraulic flow path 63 and the first piston chamber 67 are shut off, the pressure oil of the supply pressure Pa acts only on the small diameter portion 70 of the first stepped piston 66, and the first stepped piston 66 is on the other side. Move to the right (Fig. 7).
As a result, the motor capacity of the variable displacement hydraulic motor 61 increases.

  The control device 62 is a CHP valve (constant hose power valve), and automatically adjusts the motor capacity to control the horsepower constant. That is, the motor capacity is adjusted so that the supply pressure Pa is constant. The control device 62 includes a first switching control valve (corresponding to a spool valve) 73 and an electromagnetic proportional pressure reducing valve 74 for adjusting the motor capacity according to an external command, and a second switching for automatically adjusting the motor capacity. And a control valve (corresponding to a pressure compensation valve) 75. In the control device 62, when the motor capacity is increased by an external command, the pressure of the pilot oil P1 is reduced by the electromagnetic proportional pressure reducing valve 74. Then, the force by which the piston 86 in the third piston chamber 80 presses the spool 73a to one side (left side in FIG. 7) becomes weak, and the spool 73a is moved to the other side (right side in FIG. 7) by the spring force of the spring 73b. ) Thus, the spool 73a is disposed at the capacity increasing position.

  At this time, since the first piston chamber 67 communicates with the tank T, the first stepped piston 66 moves to the other side, and the motor capacity increases. Conversely, when the motor capacity is decreased by an external command, the pressure of the pilot oil P 1 is increased by the electromagnetic proportional pressure reducing valve 74. Then, the force with which the piston 86 presses the spool 73a to one side (left side in FIG. 7) becomes strong, and the spool 73a moves to one side (left side in FIG. 7) against the spring force. As a result, the spool 73a moves to the capacity decreasing position. Then, since the first piston chamber 67 is connected to the hydraulic flow path 63, the first stepped piston 66 moves to one side (left side in FIG. 7), and the motor capacity decreases.

  When the supply pressure Pa increases, the pressure of the pressure oil flowing from the hydraulic flow path 63 into the fourth piston chamber 81 increases, so that the force acting on the small diameter portion 84 of the second stepped piston 83 acts on the large diameter portion 85. It becomes bigger than the power to do. When the supply pressure Pa reaches the reference pressure Pset1, the second stepped piston 83 moves the spool 75a to the capacity increase position against the spring force of the spring 75b. Then, since the first piston chamber 67 and the oil tank T are connected, the pressure in the first piston chamber 67 decreases, and the first stepped piston 66 moves to the other side (right side in the figure) Motor capacity increases.

  When the motor capacity increases, the supply pressure Pa decreases, and when the motor pressure increases to the reference pressure Pset1, the second stepped piston 83 cannot move the spool 75a to the other side (the right side in FIG. 7), and the spool 75a Is moved to one side (left side in FIG. 7) and disposed at the capacity decreasing position shown in FIG. As a result, the hydraulic flow path 63 and the first piston chamber 67 are connected, and the first stepped piston 66 moves to one side (left side in FIG. 7), and the motor capacity decreases. Such operations are sequentially repeated so that the supply pressure Pa is maintained in the vicinity of the reference pressure Pset1, and the horsepower is kept constant (see, for example, Patent Document 2).

The conventional example 2 is a technique disclosed as the conventional example 2 in paragraphs [0003], [0004], and [0011] to [0014] of Patent Document 2.
Japanese Patent Laid-Open No. 5-126103 JP 2001-317442 A

  The control apparatus for a variable displacement hydraulic motor according to the above conventional example 1 selects the high pressure side pressure among the pressures on the winding side flow path and the lowering side flow path of the motor drive circuit of the variable displacement hydraulic motor. A constant pressure is controlled by causing the pressure compensation valve to act as a pilot pressure via a valve (shuttle valve). By the way, when such a variable displacement hydraulic motor is used for driving a winch, a counter balance valve is provided in the control device in order to prevent the variable displacement hydraulic motor from stalling in the load direction. Since the counter balance valve is provided with damping performance on the valve opening direction side in order to ensure the operation stability, the valve opening speed of the counter balance valve is slow. Therefore, the following problems to be solved arise during the lowering operation.

  In other words, when only a hook that does not carry a suspended load is lowered or when a hook that carries a lightweight suspended load is lowered, this occurs in the hoisting-side flow path to hold the suspended load. The motor holding pressure is low. On the other hand, at the start of the lowering operation, due to the damping performance of the counter balance valve interposed in the winding side flow path, the spool opening of the counter balance valve remains small for a while. It takes time to reach the counter balance state. When the motor holding pressure generated in the winding side flow path is low, the differential pressure across the spool opening of the counter balance valve is also small, so it takes time to reach a large spool opening that balances with the pump flow rate (motor supply flow rate). In the meantime, the lowering flow path and the flow path between the variable displacement hydraulic motor of the winding flow path and the counter balance valve are in a high pressure state. Therefore, despite the small load caused by the suspended load, a high pressure is introduced into the pilot oil chamber of the pressure compensation valve and constant pressure control is applied. As a result, the motor capacity of the variable displacement hydraulic motor is maximized. For this reason, at the start of lowering of a light load, the rotational speed of the variable displacement hydraulic motor is restricted to a low speed, and the winch lowering speed becomes low. That is, at the start of lowering a light load, there is a problem that acceleration is extremely deteriorated and work efficiency is lowered.

  In the case of the conventional example 2, as shown in FIG. 7, the operation of the spool 75 a of the second switching control valve (corresponding to the pressure compensation valve) 75 is caused by the supply pressure introduced into the fourth piston chamber 81. It is controlled by a second stepped piston 83 that operates by a differential pressure (Ps) between Pa (motor driving pressure Pa) and a supply pressure Pb (motor driving pressure Pb) introduced into the fifth piston chamber 82. Therefore, since the high pressure state of the lowering flow path and the flow path between the variable displacement hydraulic motor of the winding flow path and the counter balance valve is canceled as a pressure control valve, as in Conventional Example 1, At the start of lowering a light load, there is no problem that the winch lowers at a lower speed.

  However, during the lowering operation when the suspended load is heavy, there is a counterbalance action of the counterbalance valve, and the pressure fluctuations in the lowering flow path (supply side) and the lifting flow path (discharge side) are in reverse phase. (In the case of the conventional example 2, the circuit tends to become unstable (such as hunting). There is a drawback that vibration is likely to occur.

  Therefore, the object of the present invention is to prevent an unsatisfactory acceleration in the lowering speed at the start of winch light load lowering, and to cause unstable behavior such as hunting during heavy load lowering operation. It is an object of the present invention to provide a variable displacement hydraulic motor control device that is excellent in workability and stability.

  In order to solve the above problems, the means adopted by the variable displacement hydraulic motor control device according to claim 1 of the present invention is the first piston that increases the tilt angle of the motor and the second that decreases the tilt angle. Supply of fluid to the second piston by moving through a spool that includes a hydraulic piston having a piston and switches supply of fluid to the second piston in accordance with pilot pressure, and a feedback lever that transmits displacement of tilting The motor drive pressure supplied to the motor through a motor drive circuit comprising a winding side flow path and a lowering side flow path is provided with a predetermined value. Pressure compensation valve that stops the supply of supply pressure to the second piston and controls the motor drive pressure so as not to exceed a predetermined value, and a counter balun that prevents stalling in the load direction. In the control apparatus for a variable displacement hydraulic motor provided with a valve, a hoisting-side pilot channel is connected to a pilot oil chamber opposed to a set spring of the pressure compensation valve from the hoisting-side channel, and the lowering-side channel The pilot oil chamber on the set spring side communicates with the lower pilot passage, and a pressure compensation switching valve is interposed in the lower pilot passage, and when the lowering operation is performed, When the pressure difference between the pressure of the flow path and the pressure of the lowering side flow path reaches a predetermined pressure equal to or lower than the set value of the pressure compensation valve, the pressure compensation type switching valve is shut off from the lowering side pilot flow path. In addition, overload prevention control switching means for switching the pilot oil chamber of the pressure compensation valve to a position communicating with the tank is provided.

  The variable displacement hydraulic motor control device according to claim 2 of the present invention employs the variable displacement hydraulic motor control device according to claim 1, wherein the pressure compensation switching valve is a hydraulic pilot switching valve. The overload prevention control switching means is switched by a lowering operation pilot pressure, and a lowering operation detecting hydraulic pilot switching valve for outputting a pilot pressure of a pilot pressure source to the secondary side, and a hoisting side flow path The pressure between the variable displacement hydraulic motor and the counter balance valve is guided in the direction opposite to the set pull, and the pressure in the lowering side flow path is guided in the same direction as the set spring, and the pressure in the winding side flow path is Is switched when the differential pressure between the pressure of the lowering side flow path and the pressure of the pressure compensating valve reaches a predetermined pressure or lower, and the secondary side flow of the lowering operation detecting hydraulic pilot switching valve is switched. The pressure is characterized in that it consists of a hydraulic switching valve leading to the pilot oil chamber of the pressure compensation system switching valve.

  The variable displacement hydraulic motor control apparatus according to claim 3 of the present invention employs the variable displacement hydraulic motor control apparatus according to claim 1, wherein the pressure compensation switching valve is an electromagnetic switching valve. The overload prevention control switching means includes a lowering operation pilot pressure detection sensor that detects a lowering operation pilot pressure, and a hoisting side that detects a pressure between the variable displacement hydraulic motor in the hoisting side flow path and the counter balance valve. A pressure detection sensor, a lowering pressure detection sensor for detecting the pressure of the lowering passage, and a pressure detection signal are input from each of the pressure detection sensors, and are obtained from the pressure signal of the hoisting passage during the lowering operation. When the pressure difference between the pressure obtained and the pressure obtained from the pressure detection signal of the lowering side flow path reaches a predetermined pressure equal to or lower than the set value of the pressure compensation valve, a switching signal is sent to the pressure compensation switching valve. And it is characterized in that comprising a force controller.

  In the control apparatus for a variable displacement hydraulic motor according to claim 1 of the present invention, when the hook carrying a lightweight load is lowered, for the damping performance of the counter balance valve, for a while, While the lower side flow path and the flow path between the variable displacement hydraulic motor of the winding side flow path and the counter balance valve are in a high pressure state, the pressure of the winding side flow path and the lower side flow path The pressure compensation switching valve does not switch until the pressure difference from the pressure reaches a predetermined pressure that is equal to or less than the set value of the pressure compensation valve.

  Therefore, according to the control apparatus for a variable displacement hydraulic motor according to claim 1 of the present invention, the pressure compensation valve functions as a differential pressure control valve, and the winch lowering speed does not become low. The work efficiency is not reduced. On the other hand, during the lowering operation when the suspended load is a heavy load, the counterbalance valve has a counterbalance action, but the pressure difference between the pressure on the winding side channel and the pressure on the lowering side channel is set by the pressure compensation valve. When the pressure reaches a predetermined pressure below the value, the pressure compensation switching valve is switched, the lowering pilot passage is shut off, and the pilot oil chamber of the pressure compensation valve communicates with the tank. Since it functions as an absolute pressure control valve only by the pressure on the side (the discharge side at the time of winding), there is no instability in the circuit and no unstable behavior such as hunting occurs.

  According to the control device for a variable displacement hydraulic motor according to claim 2 of the present invention, the pressure compensation switching valve has a pressure difference between the pressure of the winding side channel and the pressure of the lowering side channel of the pressure compensation valve. The pressure is switched by introducing the pressure in the secondary flow path of the hydraulic pilot switching valve for detecting the lowering operation from the hydraulic switching valve that switches when a predetermined pressure equal to or lower than the set value is reached into the pilot oil chamber.

  According to the control device for the variable displacement hydraulic motor according to the third aspect of the present invention, the pressure compensation switching valve includes the pilot pressure detection sensor for detecting the lowering operation pilot pressure, and the variable displacement hydraulic of the hoisting side passage. Detection values are input from a motor pressure detection sensor that detects the pressure between the motor and the counter balance valve and a lowering pressure detection sensor that detects the pressure in the lowering passage, and are switched by a switching signal from the controller.

Hereinafter, control devices for variable displacement hydraulic motors according to Embodiments 1 and 2 of the present invention will be described.
First, a control apparatus for a variable displacement hydraulic motor according to a first embodiment of the present invention will be described with reference to FIG. 1 of its hydraulic circuit diagram.

  In a swash plate type axial piston motor 1 that changes the tilt angle of a swash plate, that is, a variable displacement hydraulic motor (hereinafter referred to as a hydraulic motor) 1, a first piston 2 a and a second piston 2 a disposed opposite to a hydraulic piston 2. , 2b, the piston stroke of the hydraulic motor 1 changes, and the motor capacity of the hydraulic motor 1 (necessary oil amount per rotation) is changed. Yes. A control device for controlling the motor capacity of the hydraulic motor 1 is combined with the hydraulic motor 1 and includes a spool valve 3, a connecting means 4, a pressure compensation valve 5, and the like in addition to a hydraulic piston 2 for driving a swash plate. Has been.

  The hydraulic motor 1 is supplied from a hoisting side channel 6 and a lowering side channel 7 to which hydraulic oil of a motor supply pressure Pa or Pb (hereinafter referred to as motor driving pressure) is switched and supplied from a hydraulic oil supply source (not shown). A motor drive circuit is connected. The pilot oil chamber of the spool valve 3 communicates with a pilot flow path 13 on which a pilot pressure Pi arbitrarily set by an operator's operation from a pressure generating source acts. The flow path 8 branched from the winding side flow path 6 communicates with the pump port of the pressure compensation valve 5, and the actuator port of the pressure compensation valve 5 communicates with the pump port of the spool valve 3 via the flow path 9. ing.

The actuator port of the spool valve 3 communicates with the pressure receiving portion of the second piston 2b through the flow path 10 to reduce the tilt angle of the swash plate and reduce the motor capacity of the hydraulic motor 1.
A winding side pilot channel 11 branches from the channel 8, and the winding side pilot channel 11 communicates with a pilot oil chamber that opposes the set spring 5 b of the pressure compensation valve 5. A flow path 12 is branched from the winding side pilot flow path 11, and the flow path 12 increases the tilt angle of the swash plate to increase the motor capacity of the hydraulic motor 1. Communicating with The pressure receiving portion of the second piston 2b is set to have a larger pressure receiving area than the pressure receiving portion of the first piston 2a, and when the motor driving pressure Pa or Pb of the same pressure acts on both, the second piston 2b When pushed, the tilt angle of the swash plate is reduced.

In the pilot oil chamber on the set spring 5 b side of the pressure compensation valve 5, there is a lowering pilot passage 14 in which a hydraulic pilot switching type pressure compensation switching valve 18 is interposed from the lowering passage 7. Communicate. The pressure compensation system switching valve 18 is configured such that when the hydraulic motor 1 is operated to the lowering side, the pressure difference between the pressure of the winding side channel 6 and the pressure of the lowering side channel 7 is the pressure compensation. When a predetermined pressure equal to or lower than the set value of the valve 5 is reached, the pressure is switched by the pilot pressure from the overload prevention control switching means 20 having the configuration described later, the lowering pilot passage 14 is shut off, and the pressure compensation valve The pressure compensation valve 5 functions as an absolute pressure control type valve so that the pilot oil chamber on the side of the set spring 5b is connected to the tank T.
Of course, when the pressure compensation switching valve 18 is not switched, the pressure of the winding side passage 6 is introduced into the pilot oil chamber opposed to the set spring 5b and the winding side pilot passage 14 is wound. Since the pressure in the lower channel 7 is introduced, the pressure compensation valve 5 functions as a differential pressure control type valve.

The overload prevention control switching means 20 is a hydraulic pressure for supplying a pilot switching valve 21 for detecting the lowering operation and a pilot pressure from the pilot switching valve 21 for detecting the lowering operation to the pilot oil chamber of the pressure compensation type switching valve 18. It consists of a switching valve 23 and the like. More specifically, the pilot switching valve 21 for detecting the lowering operation is switched by the lowering pressure Pc, and a pilot pressure P ₀ of a pilot pressure source (not shown) is supplied to the hydraulic switching valve 23 via the secondary side passage 22. Output. This hydraulic switching valve 23 is a two-position switching valve, and the pressure between the hydraulic motor 1 and the counter balance valve 6a in the winding side flow path 6 is placed in the pilot oil chamber on the side opposite to the set spring 23b of the hydraulic switching valve 23. Is introduced through the flow path 17. Further, the pressure of the lowering flow path 7 is introduced through the flow path 16 into the pilot oil chamber on the set spring 23 b side. A flow path 24 communicates from the hydraulic pressure switching valve 23 to the pilot oil chamber of the pressure compensation system switching valve 18.

  Reference numeral 15a denotes an overload relief valve. The flow path 15 communicates between the counter balance valve 6a of the winding-side flow path 6 and the branching section of the flow path 8 and the lower-side flow path 7. It is provided to protect the devices such as motors by cutting the excessive surge pressure generated during the sudden stop of the lowering.

Hereinafter, the operation mode of the hydraulic motor control device according to the first embodiment will be described. Pib is introduced into the pilot oil chamber of the spool valve 3 as a value of the external pilot pressure Pi from the pilot flow path 13, and the lowering operation is performed in a state where the motor capacity of the hydraulic motor 1 is the minimum capacity qa. Next, the operation of the pressure compensation valve 5 when the lowering pilot pressure is generated will be described. At this time, the pilot switching valve 21 for detecting the lowering operation is switched by the lowering pilot pressure Pc, and the pilot pressure P ₀ of the pilot pressure source is transmitted to the secondary side flow path 22.

First, the case where the lowering load is a light load will be described. In this case, due to the tamping performance of the counter balance valve 6a, the spool opening of the counter balance valve 6a remains small for a while at the start of the lowering operation, and it takes time to reach the counter balance state. Since the holding pressure generated according to the load of the suspended load is low and the differential pressure across the spool opening of the counter balance valve 6a is also small, it takes time to reach a large spool opening that balances with the pump flow rate (motor supply flow rate). In the meantime, both sides of the lowering side channel 7 and the winding side channel 6 are in a high pressure state. For this reason, the pressures of the flow paths 17 and 16 branched from the lower-side flow path 7 and the hoist-side flow path 6 and communicating with both pilot oil chambers of the hydraulic switching valve 23 are both in a high pressure state. Is small and does not reach the predetermined pressure P _W , the hydraulic switching valve 23 is not switched and is maintained at the position shown in FIG.

  In this state, the flow path 24 that communicates from the hydraulic switching valve 23 to the pilot oil chamber of the pressure compensation switching valve 18 communicates with the tank T via the hydraulic switching valve 23, and the pressure compensation switching valve 18 is switched. Therefore, the pressure in the lowering flow path 7 is introduced into the pilot chamber on the set spring 5 b side of the pressure compensation valve 5 via the lowering pilot path 14. On the other hand, since the pressure of the winding flow path 6 is introduced into the pilot oil chamber on the side opposed to the set spring 5b via the flow path 8 and the winding side pilot flow path 11, the pressure compensation valve 5 is controlled by differential pressure control. Acts as a mold valve. Therefore, even if both sides of the lowering flow path 7 and the winding flow path 6 are in a high pressure state, the pressure compensation valve 5 does not operate, so the motor capacity does not increase, and the hydraulic motor 1 has the minimum capacity qa. Since it continues to rotate and the lowering speed of the winch is lowered at the maximum speed, the acceleration performance is good.

  Next, a case where the lowering load is a heavy load will be described. At the start of the lowering operation, the counter balance valve 6a is affected by the damping performance. However, since the holding pressure generated in the winding side flow path 6 according to the suspended load is large, the counter balance valve 6a The differential pressure is large, the spool opening degree that balances with the pump flow rate (motor supply flow rate) may be small, and the time to reach the opening degree is short. When the counter balance valve 6a is in the counter balance state, the supply pressure at the time of lowering on the lowering flow path 7 side is low, and the holding pressure at the time of lowering on the hoisting side flow path 6 is high.

When the differential pressure between the holding pressure at the time of lowering and the supply pressure at the time of lowering, that is, the pressure difference between the pressure in the winding side channel 6 and the pressure in the lowering side channel 7 reaches a predetermined pressure _PW , the hydraulic pressure is switched. The valve 23 is switched, and the flow path 22 and the flow path 24 are communicated to introduce the pilot pressure P ₀ of the pilot pressure source into the pilot oil chamber of the pressure compensation system switching valve 18. Switch. Accordingly, the pilot flow path 14 communicates with the tank T, while the winding side flow path 6 through the flow path 8 and the winding side pilot flow path 11 are connected to the pilot oil chamber on the side opposite to the set spring 5 b of the pressure compensation valve 5. Thus, since only the holding pressure at the time of lowering is introduced, the pressure compensation valve 5 functions as an absolute pressure control type valve.

As described above, since the winding-side flow path 6 has a high pressure operation, the pressure of the winding-side passage 6 reaches P _S, since the pressure compensating valve 5 actuated, the hydraulic motor 1 by constant pressure control Is done. When the unwinding load is a heavy load, there is a counterbalance action of the counterbalance valve 6a, and the pressure fluctuations on the supply side and the discharge side are likely to be in opposite phases. Therefore, the pressure compensation valve 5 does not amplify the pressure fluctuation and generate vibration such as hunting.

  Next, a hydraulic motor control apparatus according to Embodiment 2 of the present invention will be described with reference to FIG. 2 of its hydraulic circuit diagram. The second embodiment differs from the first embodiment in that the pressure compensation switching valve is replaced with an electromagnetic switching valve, and the main part is the main part of the hydraulic circuit diagram according to the first embodiment. Since the configuration is the same as that of the unit, the same reference numerals are given to the same components, and differences will be mainly described.

  An electromagnetic switching type pressure compensation switching valve 18 that is switched and controlled by a controller 31 is connected to a lowering pilot channel 14 that communicates from the lowering path 7 to the pilot oil chamber on the set spring 5 b side of the pressure compensation valve 5. Is intervening. The controller 31 includes a lowering operation pilot pressure detection sensor 32 for detecting the pilot pressure in the lowering pilot flow path of the remote control valve 19 for controlling the rotation speed and direction of the hydraulic motor 1, and the lowering flow path 7. The pressure detection signal is input from the lowering pressure detection sensor 33 for detecting the pressure of the hoisting side and the hoisting side pressure detection sensor 34 for detecting the pressure between the hydraulic motor 1 of the hoisting side passage 6 and the counter balance valve 6a. It has become.

  The controller 31 determines from the pressure detection signal from the lowering operation pilot pressure detection sensor 32 whether the remote control valve 19 is operated on the lowering side or the winding side. When the controller 31 determines that the operation is performed on the lowering side, the pressure obtained from the pressure signal of the winding side flow path 6 input from the winding side pressure detection sensor 34 and the lowering side pressure detection are detected. The differential pressure from the pressure obtained from the pressure detection signal of the lowering side flow path 7 input from the sensor 33 is calculated. When the differential pressure obtained by the calculation reaches a predetermined pressure Pw that is equal to or lower than a set value of the pressure compensation valve 5, a switching signal is output to the pressure compensation system switching valve 18. The overload prevention control switching means 30 in the second embodiment includes a controller 31, a lowering operation pilot pressure detection sensor 32, a lowering side pressure detection sensor 33, and a hoisting side pressure detection sensor.

  A mode of operation of the hydraulic motor control device according to the second embodiment of the present invention will be described. Pib is introduced into the pilot oil chamber of the spool valve 3 as a value of the external pilot pressure Pi from the pilot flow path 13, and the lowering operation is performed in a state where the motor capacity of the hydraulic motor 1 is the minimum capacity qa. Next, the operation of the pressure compensation valve 5 when the lowering pilot pressure is generated will be described. At this time, the lowering pilot pressure Pc is detected by the lowering operation pilot pressure detection sensor 32, and the lowering operation detection signal is input to the controller 31.

First, the case where the lowering load is a light load will be described. In this case, due to the tamping performance of the counter balance valve 6a, the spool opening of the counter balance valve 6a remains small for a while at the start of the lowering operation, and it takes time to reach the counter balance state. Since the holding pressure generated according to the load of the suspended load is low and the differential pressure across the spool opening of the counter balance valve 6a is also small, it takes time to reach a large spool opening that balances with the pump flow rate (motor supply flow rate). In the meantime, both sides of the lowering side channel 7 and the winding side channel 6 are in a high pressure state. The pressures of the lowering side flow path 7 and the hoisting side flow path 6 are input to the controller 31 as pressure detection signals detected by the hoisting side pressure detection sensor 34 and the lowering side pressure detection sensor 33. Since the pressure differential pressure obtained from the signal is small and does not reach the predetermined pressure P _W , no switching signal is output from the controller 31 to the pressure compensation switching valve 18.

  In this state, the pressure in the lowering flow path 7 is introduced into the pilot chamber on the set spring 5 b side of the pressure compensation valve 5 through the lowering pilot path 14. On the other hand, since the pressure of the winding flow path 6 is introduced into the pilot oil chamber on the side opposed to the set spring 5b via the flow path 8 and the winding side pilot flow path 11, the pressure compensation valve 5 is controlled by differential pressure control. Acts as a mold valve. Therefore, even if both sides of the lowering flow path 7 and the winding flow path 6 are in a high pressure state, the pressure compensation valve 5 does not operate, so the motor capacity does not increase, and the hydraulic motor 1 has the minimum capacity qa. Since it continues to rotate and the lowering speed of the winch is lowered at the maximum speed, the acceleration performance is good.

  Next, a case where the lowering load is a heavy load will be described. At the start of the lowering operation, the counter balance valve 6a is affected by the damping performance. However, since the holding pressure generated in the winding side flow path 6 according to the suspended load is large, the counter balance valve 6a The differential pressure is large, the spool opening degree that balances with the pump flow rate (motor supply flow rate) may be small, and the time to reach the opening degree is short. When the counter balance valve 6a is in the counter balance state, the supply pressure at the time of lowering on the lowering flow path 7 side is low, and the holding pressure at the time of lowering on the hoisting side flow path 6 is high.

The pressures of the lowering side flow path 7 and the hoisting side flow path 6 are input to the controller 31 as pressure detection signals detected by the hoisting side pressure detection sensor 34 and the lowering side pressure detection sensor 33. When the differential pressure of the pressure obtained from the signal reaches a predetermined pressure _PW , a switching signal is output from the controller 31 to the pressure compensation system switching valve 18, so that the pressure compensation system switching valve 18 is switched. Accordingly, the pilot flow path 14 communicates with the tank T, while the winding side flow path 6 through the flow path 8 and the winding side pilot flow path 11 are connected to the pilot oil chamber on the side opposite to the set spring 5 b of the pressure compensation valve 5. Thus, since only the holding pressure at the time of lowering is introduced, the pressure compensation valve 5 functions as an absolute pressure control type valve.

As described above, since the winding-side flow path 6 has a high pressure operation, the pressure of the winding-side passage 6 reaches P _S, since the pressure compensating valve 5 actuated, the hydraulic motor 1 by constant pressure control Is done. When the unwinding load is a heavy load, there is a counterbalance action of the counterbalance valve 6a, and the pressure fluctuations on the supply side and the discharge side are likely to be in opposite phases. Therefore, the pressure compensation valve 5 does not amplify the pressure fluctuation and generate vibration such as hunting.

  Note that the hydraulic motor control devices according to the first and second embodiments of the present invention are only specific examples of the present invention, so that the hydraulic motor control device according to the first and second embodiments is a form of the control device. It is not limited, and design changes and the like can be freely made without departing from the technical idea of the present invention.

1 is a hydraulic circuit diagram of a control device for a hydraulic motor according to Embodiment 1 of the present invention. It is a hydraulic circuit diagram of the control apparatus of the hydraulic motor which concerns on Embodiment 2 of this invention. FIG. 10 is a hydraulic circuit diagram of a control device according to Conventional Example 1 that performs hydraulic motor capacity control and overload prevention control. It is a figure which shows the relationship between the input pilot pressure by the control apparatus of a hydraulic motor, and a motor capacity | capacitance concerning the prior art example 1. FIG. It is a figure which concerns on the prior art example 1 and shows the relationship between the motor drive pressure of a hydraulic motor, and a motor capacity | capacitance. It is a figure which concerns on the prior art example 1 and shows the relationship between the motor output torque of a hydraulic motor, and a motor rotational speed. FIG. 10 is a hydraulic circuit diagram in which a control device for a hydraulic motor is simplified according to the second conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hydraulic motor, 2 ... Hydraulic piston, 2a ... 1st piston, 2b ... 2nd piston, 3 ... Spool valve, 4 ... Connection means, 5 ... Pressure compensation valve, 5b ... Set spring, 6 ... Winding side flow path , 6a ... counter balance valve, 7 ... lowering side flow path, 8 ... flow path, 9 ... flow path, 10 ... flow path 11 ... winding side pilot flow path, 12 ... flow path, 13 ... pilot flow path, 14 ... Lower pilot flow path, 15 ... flow path, 15a ... overload relief valve, 16 ... flow path, 17 ... flow path, 18 ... pressure compensation switching valve, 19 ... remote control valve, 20 ... overload prevention control switching means , 21 ... Pilot switching valve for detecting the lowering operation, 22 ... Secondary flow path, 23 ... Hydraulic switching valve, 23b ... Set spring, 24 ... Flow path 30 ... Overload prevention control switching means, 31 ... Controller, 32 ... Lowering operation Pilots the pressure detection sensor, 33 ... lowering side pressure detecting sensor, 34 ... winding side pressure detecting sensor

Claims (3)

  A hydraulic piston having a first piston for increasing the tilt angle of the motor and a second piston for decreasing the tilt angle; a spool for switching the supply of fluid to the second piston in accordance with the pilot pressure; It comprises a sleeve that moves through a feedback lever that transmits displacement and shuts off the supply of fluid to the second piston, and includes a spool valve that uniquely defines the tilt angle, and a winding side channel and a winding side channel When the motor drive pressure supplied to the motor through the motor drive circuit consisting of the above reaches a predetermined value, the supply pressure supply to the second piston is stopped and the pressure compensation is controlled so that the motor drive pressure does not exceed the predetermined value. In a control device for a variable displacement hydraulic motor having a valve and a counterbalance valve for preventing stalling in a load direction, the control device is opposed to a set spring of the pressure compensation valve. A pilot-side pilot channel is connected from the winding-side channel to the pilot oil chamber, and a pilot-side pilot channel is connected from the lower-side channel to the pilot oil chamber on the set spring side. When a pressure compensation method switching valve is interposed in the passage and the lowering operation is being performed, the pressure difference between the pressure on the winding side channel and the pressure on the lowering side channel is the set value of the pressure compensation valve When the following predetermined pressure is reached, the overload prevention control switching means switches the pressure compensation switching valve to a position where the lowering pilot passage is shut off and the pilot oil chamber of the pressure compensation valve communicates with the tank. A control apparatus for a variable displacement hydraulic motor, comprising:   The pressure compensation switching valve is a hydraulic pilot switching valve, and the overload prevention control switching means is switched according to a lowering operation pilot pressure, and a lowering operation for outputting the pilot pressure of the pilot pressure source to the secondary side. The pressure between the detection hydraulic pilot switching valve, the variable displacement hydraulic motor in the hoist side flow path and the counter balance valve is guided in a direction opposite to the set pull, and the pressure in the lower side flow path is the same as that of the set spring. Is switched when the differential pressure between the pressure of the winding side channel and the pressure of the lowering side channel reaches a predetermined pressure equal to or lower than the set value of the pressure compensation valve, and the lowering operation is detected. 2. The variable displacement hydraulic motor according to claim 1, further comprising: a hydraulic switching valve that guides a pressure in a secondary side passage of the hydraulic pilot switching valve for use to a pilot oil chamber of the pressure compensation switching valve. The control device.   The pressure compensation system switching valve is an electromagnetic switching valve, and the overload prevention control switching means includes a lowering operation pilot pressure detection sensor for detecting a lowering operation pilot pressure, and a variable displacement hydraulic motor of the hoisting side passage. Winding pressure detection sensor for detecting the pressure between the counter balance valve, the lower pressure detection sensor for detecting the pressure of the lower flow path, and pressure detection signals are input from the respective pressure detection sensors, When the differential pressure between the pressure obtained from the pressure signal of the winding side channel and the pressure detection signal of the lowering side channel during operation reaches a predetermined pressure equal to or lower than the set value of the pressure compensation valve 2. The control apparatus for a variable displacement hydraulic motor according to claim 1, further comprising a controller that outputs a switching signal to the pressure compensation switching valve.

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