JP2013151219A - Mixer drum driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mixer drum driving device having a fluid pressure motor that smoothly stops a mixer drum.SOLUTION: A mixer drum driving device is configured such that a mixer drum 1 is rotationally driven by an oil hydraulic motor (a fluid pressure motor) 81. The device includes first/second supply/discharge passages 51, 52 that supply/discharge operating oil to/from the oil hydraulic motor 81. The device also includes a motor load pressure relief passage 21 that relieves the load pressure of operating fluid, generated in a volume chamber of the fluid pressure motor 81, to the low-pressure side through one of the first/second supply/discharge passages 51, 52 when the drive of the fluid pressure motor 81 is stopped after a command to stop the drive of the mixer drum 1 is issued.

Description

  The present invention relates to a mixer drum driving device that drives a mixer drum by a fluid pressure motor.

  A mixer truck for carrying ready-mixed concrete is equipped with a mixer drum for stirring and discharging ready-mixed concrete supplied from a hopper or the like.

  A mixer drum driving device that drives this type of mixer drum includes a hydraulic motor that drives the mixer drum. The hydraulic motor is supplied and discharged with hydraulic oil from a hydraulic source via a direction switching valve, and the rotation direction, rotation speed, and rotation stop of the mixer drum are switched according to the position of the direction switching valve.

  When stopping the rotation of the mixer drum, the communication between the supply and discharge ports of the hydraulic motor is blocked by switching the direction switching valve to the neutral position.

  The device disclosed in Patent Document 1 throttles the flow of hydraulic oil between the supply and discharge ports of the hydraulic motor in the process of switching the direction switching valve to the neutral position, and finally blocks this flow. Yes.

JP 59-106333 A

  By the way, when the ready-mixed concrete is put into the mixer drum and the mixer drum is rotated in one direction (see arrow B in FIG. 5), when the rotating operation of the mixer drum is temporarily stopped, A situation occurs in which the load is biased to one of the inner walls of the mixer drum and the load is applied to the mixer drum.

  If this situation continues, the mixer drum will drive the hydraulic motor due to the unbalanced load of the ready-mixed concrete, and the hydraulic motor will be discontinuous in the reverse direction (see arrow A in FIG. 5) when driven before stopping due to internal leakage of hydraulic oil. Stop after rotating automatically. For this reason, a problem arises that the mixer drum rotates discontinuously and the mixer drum shakes the mixer truck.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a mixer drum driving device in which a fluid pressure motor smoothly stops the mixer drum.

  The present invention comprises a positive displacement fluid pressure motor that rotationally drives the mixer drum, and first and second supply / discharge passages that supply and discharge the working fluid to and from the fluid pressure motor, and a command to stop the drive of the mixer drum is issued. When the drive of the fluid pressure motor is stopped, motor load pressure release means for releasing the load pressure of the working fluid generated in the volume chamber of the fluid pressure motor to the low pressure side through one of the first and second supply / discharge passages is provided. It is characterized by.

  In the present invention, when the driving of the mixer drum is stopped, the load pressure of the fluid pressure motor is released to the low pressure side through one of the first and second supply / discharge passages in a situation where the torque due to the uneven load of the mixer drum acts on the mixer drum. As a result, the fluid pressure motor continuously rotates in the opposite direction to that before driving, and the mixer drum stops.

  Thereby, after the driving of the mixer drum is stopped, the fluid pressure motor is prevented from rotating intermittently due to the internal leakage of the working fluid, and the shaking of the mixer drum can be suppressed.

1 is a hydraulic circuit diagram of a mixer drum driving device showing a first embodiment of the present invention. It is sectional drawing of a direction switching valve. FIG. 4 is a hydraulic circuit diagram of a mixer drum driving device showing a second embodiment of the present invention. FIG. 5 is a hydraulic circuit diagram of a mixer drum driving device showing a third embodiment of the present invention. It is a figure which shows the mode in a mixer drum when driving of a mixer drum is stopped.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(First embodiment)
The mixer drum driving device shown in FIG. 1 is mounted on a mixer truck that transports ready-mixed concrete and the like.

  The mixer drum driving apparatus uses hydraulic oil (oil) as the working fluid, but a hydraulic fluid such as a water-soluble alternative liquid may be used instead of the hydraulic oil.

  The mixer drum driving device stores a mixer drum 1 that stirs a container such as ready-mixed concrete, a motor unit 80 that drives the mixer drum 1, a pump unit 50 that serves as a working hydraulic pressure source (a working fluid pressure source), and hydraulic oil. It is comprised by the tank 90 and the hydraulic piping etc. which connect these.

  The motor unit 80 includes a hydraulic motor (fluid pressure motor) 81, and the hydraulic motor 81 rotationally drives the mixer drum 1 via the transmission 2.

  For the hydraulic motor 81, for example, a swash plate type piston motor is used as a positive displacement fluid pressure motor. First and second supply / discharge passages 51 and 52 for supplying and discharging hydraulic oil are connected to the supply and discharge ports 85 and 86 of the hydraulic motor 81. The hydraulic motor 81 is rotated in both forward and reverse directions by pressurized hydraulic oil selectively supplied from the motor unit 80 through the first and second supply / discharge passages 51 and 52.

  A pair of relief valves 82 and 84 are interposed between the first and second supply / discharge passages 51 and 52 of the motor unit 80. When the pressure difference between the first and second supply / discharge passages 51 and 52 rises above a predetermined value, the relief valves 82 and 84 open, and the charge passage 58 extends from one of the first and second supply / discharge passages 51 and 52. The operating hydraulic pressure is released.

  A drain passage 91 is provided between the motor unit 80 and the tank 90. The drain passage 91 communicates the motor unit 80 and the tank 90. The hydraulic oil leaking into the motor housing of the hydraulic motor 81 is returned to the tank 90 through the in-housing drain passage 87 and the drain passage 91. An oil cooler 92 is interposed in the drain passage 91, and the hydraulic oil is cooled by the oil cooler 92. The oil cooler 92 is a well-known one having a cooler body 93 and a bypass valve 94.

  A closed circuit 49 is provided between the hydraulic pump 10 of the pump unit 50 and the hydraulic motor 81 of the motor unit 80, and hydraulic oil circulates in a loop through the closed circuit 49. The closed circuit 49 includes a return passage (pump suction passage) 12 connected to the suction port of the hydraulic pump 10, a supply passage (pump discharge passage) 13 connected to the discharge port of the hydraulic pump 10, and two provided in the hydraulic motor 81. The first and second supply / discharge passages 51 and 52 are respectively connected to the supply / discharge ports. The return passage 12 is not limited to the suction port of the hydraulic pump 10 and may be communicated with the tank 90.

  The pump unit 50 includes a hydraulic pump 10 that is rotationally driven by the engine 60, a charge pump 11, a relief valve 59, a direction switching valve 20, a load sensing valve 40, a cutoff valve 70, a high-pressure selection valve 16, and the like.

  The charge pump 11 discharges hydraulic oil sucked from the tank 90 through the passage 95 to the charge passage 58. The hydraulic oil is charged into the first and second supply / discharge passages 51 and 52 from the charge passage 58 via the check valves 55 and 56.

  The charge passage 58 communicates with the tank 90 via a relief valve 59. When the pressure in the charge passage 58 rises above a predetermined value, the relief valve 59 is opened, and surplus hydraulic oil discharged from the charge pump 11 is returned to the tank 90. Thereby, when the charge pump 11 is operated, the pressure on the low pressure side of the first and second supply / discharge passages 51, 52 is maintained at a pressure higher than the set pressure of the relief valve 59. The charge passage 58 is connected to the in-housing drain passage 87 via the check valve 88.

  A part of the charge passage 58 connecting the pump unit 50 and the motor unit 80 is formed by external piping. A part of the passage 95 connecting the charge pump 11 and the tank 90 is formed by an external pipe, and a strainer 96 is interposed in the middle, and the working oil is filtered by the strainer 96. The inside of the casing of the pump unit 50 and the inside of the casing of the motor unit 80 are communicated by a drain passage 97.

  A return passage 12 and a supply passage 13 are connected to the hydraulic pump 10, and the hydraulic oil sucked from the return passage 12 is discharged to the supply passage 13. The return passage 12 is filled with hydraulic oil from the charge pump 11 via the check valve 54.

  A return passage 12, a supply passage 13, and first and second supply / discharge passages 51 and 52 are connected to the direction switching valve 20. The pressurized hydraulic oil discharged from the hydraulic pump 10 to the supply passage 13 is selectively guided to one of the first and second supply / discharge passages 51 and 52 by the direction switching valve 20, and the hydraulic oil that has driven the hydraulic motor 81 is supplied. The fluid is sucked into the hydraulic pump 10 through the return passage 12 from the other of the first and second supply / discharge passages 51 and 52.

  The direction switching valve 20 is switched to positions a, b, and c by the pilot pressure guided through the two proportional solenoid valves 4 and 5. The opening degree of the proportional solenoid valves 4 and 5 is controlled by a controller (not shown). This controller outputs a drive current to the proportional solenoid valves 4 and 5 in response to a command signal from an operation lever (not shown).

  When the mixer drum 1 is rotated forward to agitate and knead the ready-mixed concrete, one proportional solenoid valve 4 is energized by the controller. Along with this, the proportional solenoid valve 4 is opened, and the operating hydraulic pressure of the charge passage 58 is guided as a pilot pressure to one pilot chamber of the direction switching valve 20, and the direction switching valve 20 is positioned by increasing this pilot pressure. It is switched to a. As a result, the pressurized hydraulic fluid discharged from the hydraulic pump 10 is guided to the second supply / discharge passage 52, and the hydraulic motor 81 is driven in the forward rotation direction. Further, the rotational speed of the hydraulic motor 81 is changed according to the opening degree of the proportional solenoid valve 4.

  During the operation of discharging the ready-mixed concrete by reversing the mixer drum 1, the other proportional solenoid valve 5 is energized by the controller. Along with this, the proportional solenoid valve 5 is opened, and the operating hydraulic pressure of the charge passage 58 is guided to the other pilot chamber of the direction switching valve 20 as a pilot pressure, and the direction switching valve 20 is positioned by increasing this pilot pressure. is switched to b. Thereby, the hydraulic oil discharged from the hydraulic pump 10 is guided to the first supply / discharge passage 51, and the hydraulic motor 81 is driven in the reverse direction. Further, the rotational speed of the hydraulic motor 81 is changed according to the opening degree of the proportional solenoid valve 5.

  A command to stop the driving of the mixer drum 1 is issued by the operation lever, and when the driving of the mixer drum 1 is stopped, the energization of the proportional solenoid valves 4 and 5 is stopped by the controller. Along with this, the proportional solenoid valves 4 and 5 are both opened, the pilot pressure guided to both pilot chambers of the direction switching valve 20 is decreased, and the direction switching valve 20 is switched to the neutral position c. When the direction switching valve 20 is switched to the neutral position c, the communication between the first and second supply / discharge passages 51 and 52 with respect to the return passage 12 and the supply passage 13 is blocked, and the rotation operation of the hydraulic motor 81 is stopped.

  For example, a swash plate type piston pump is used as the hydraulic pump 10, and its discharge capacity is changed by the actuator 14. The actuator 14 reduces the discharge capacity of the hydraulic pump 10 as the pilot pressure guided thereby increases.

  The load sensing valve 40 is guided as a pilot pressure so that a load pressure generated in one of the first and second supply / discharge passages 51 and 52 and a pump discharge pressure in the supply passage 13 are opposed to each other. The pilot pressure guided to the actuator 14 via the actuator passage 18 is adjusted so as to be a predetermined value.

  The load sensing valve 40 includes a position a that communicates the actuator 14 with the tank side, and a position b that communicates the actuator 14 with the supply passage 13, and is held at the position a by the biasing force of the spring 43.

  First and second pilot pressure passages 41 and 42 are connected to the load sensing valve 40. The first pilot pressure passage 41 is connected to the high pressure side (load pressure side) of the first and second supply / discharge passages 51 and 52 via the high pressure selection valve 16. The second pilot pressure passage 42 is connected to the supply passage 13. As the high pressure selection valve 16, for example, a shuttle valve is used.

  The load sensing valve 40 acts in a direction in which the load pressure guided from the first pilot pressure passage 41 is switched to the position a together with the urging force of the spring 43, and the pump discharge pressure guided from the second pilot pressure passage 42 is the first pilot pressure passage. It works in the direction of switching to the position b against the load pressure guided from 41 and the urging force of the spring 43.

  The cut-off valve 70 is supplied with the pump discharge pressure of the supply passage 13 as its pilot pressure, and when the pump discharge pressure rises above a predetermined value, the pilot pressure led to the actuator 14 is increased to increase the pump discharge capacity of the hydraulic pump 10. Make it smaller.

  The cut-off valve 70 includes a position a that communicates the actuator 14 with the tank side, and a position b that communicates the actuator 14 with the supply passage 13.

  The pilot pressure passage 72 of the cutoff valve 70 is connected to the supply passage 13. The cut-off valve 70 works in the direction in which the urging force of the spring 73 is switched to the position a, and the pilot pressure (pump discharge pressure) guided from the pilot pressure passage 72 is switched to the position b against the urging force of the spring 73. work.

  When the mixer drum 1 is driven, the cut-off valve 70 is held at the position a when the pump discharge pressure is a predetermined value or less, and the actuator passage 18 connecting the load sensing valve 40 and the actuator 14 is opened. The load sensing valve 40 passes through the actuator passage 18 so that the differential pressure between the load pressure generated in one of the first and second supply / discharge passages 51 and 52 and the pump discharge pressure in the supply passage 13 becomes a predetermined value. The pilot pressure guided to the actuator 14 is adjusted.

  When the driving of the mixer drum 1 is stopped, the direction switching valve 20 is switched to the neutral position c, and the pump discharge pressure is switched as the communication between the supply passage 13 and the first and second supply / discharge passages 51 and 52 is closed. When the pressure rises beyond a predetermined value, the cut-off valve 70 responds to this and switches from position a to position b. As a result, the actuator 14 communicates with the supply passage 13 to guide the pump discharge pressure, thereby reducing the pump discharge capacity of the hydraulic pump 10.

  FIG. 5 shows a situation when the rotating operation of the mixer drum 1 is temporarily stopped when the ready-mixed concrete is put in the mixer drum 1 and the mixer drum 1 is rotated in the direction of arrow B. In this situation, the stirred concrete 9 is biased to one of the inner walls of the mixer drum 1, and an unbalanced load is applied to the mixer drum 1. If this situation continues after the driving of the mixer drum 1 is stopped, a torque that causes the mixer drum 1 to rotate the hydraulic motor 81 through the transmission 2 in the direction of arrow A opposite to that before driving is stopped by the unbalanced load of the ready-mixed concrete 9. work. In the swash plate type hydraulic motor 81, the hydraulic oil pressure (hereinafter simply referred to as “load pressure of the hydraulic motor 81”) generated in a cylinder chamber (volume chamber) (not shown) is increased by this torque. By leaking into the motor housing from the gap, the movement of stopping once after the cylinder block rotates is repeated. When the hydraulic motor 81 rotates discontinuously at a certain interval in this way, there arises a problem that the mixer drum 1 rotates discontinuously and shakes the mixer car.

  In response to this, in the present embodiment, when the driving of the mixer drum 1 in which the direction switching valve 20 is switched to the neutral position c is stopped, the motor load pressure releasing means for releasing the load pressure of the hydraulic motor 81 to the low pressure side is provided. The configuration.

  As the motor load pressure relief means, the direction switching valve 20 includes a motor load pressure relief passage 21 connecting the first and second supply / discharge passages 51 and 52 of the hydraulic motor 81, and the motor load pressure relief passage 21 is neutral. It is configured to open at position c.

  The direction switching valve 20 includes a throttle 22 that provides resistance to the hydraulic fluid flowing through the motor load pressure relief passage 21.

  FIG. 2 is a sectional view of the pump unit 50. The direction switching valve 20 is provided in the pump unit 50 and the housing 24 of the hydraulic pump 10.

  The housing 24 is formed with flow paths that respectively define the supply passage 13, the return passage 12, the first and second supply / discharge passages 51, 52, and a valve housing hole 110 that opens these flow paths. Is done.

  The direction switching valve 20 includes a spool 100 that is slidably received in the valve receiving hole 110 of the housing 24, and left and right pilot pressure chambers 35 and 36 that face both ends of the spool 100.

  The spool 100 is biased to the neutral position c shown in the figure by the biasing force of the left and right return springs 37 and 38.

  As the pilot pressure guided to the left pilot pressure chamber 35 increases, the spool 100 moves to the right against the urging force of the return spring 38 and is switched to the position b.

  As the pilot pressure guided to the right pilot pressure chamber 36 increases, the spool 100 moves to the left against the urging force of the return spring 37 and is switched to the position a.

  The spool 100 has a central supply switching land 101 that blocks communication between the first and second supply / discharge passages 51 and 52 to the supply passage 13 and a left that blocks communication of the first supply / discharge passage 51 to the return passage 12. The first discharge switching land 102 and the right second discharge switching land 103 that blocks communication of the second supply / discharge passage 52 with the return passage 12.

  First and second notches 102A and 103A are formed in the first and second discharge switching lands 102 and 103, respectively. In the illustrated neutral position c, the first notch 102A communicates between the return passage 12 and the first supply / discharge passage 51, and the second notch 103A extends between the return passage 12 and the second supply / discharge passage 52. Communicate.

  When the spool 100 is at the neutral position c shown in the drawing, the communication between the first and second supply / discharge passages 51 and 52 with respect to the supply passage 13 is blocked by the central supply switching land 101 and the first and second supply / discharge passages are also provided. The passages 51 and 52 are communicated with each other by the first notch 102A, the return passage 12, and the second notch 103A. The motor load pressure relief passage 21 includes a first notch 102A, a return passage 12, and a second notch 103A.

  Grooves 33 and 34 are formed in the valve housing hole 110 of the housing 24 so as to face the first notch 102A and the second notch 103A, respectively. A throttle 22 that provides resistance to the hydraulic fluid flowing through the motor load pressure relief passage 21 is defined between a flow path defined between the groove 33 and the first notch 102A, and 34 and the second notch 103A. And a flow path. However, the present invention is not limited thereto, and a notch may be formed in the valve housing hole 110, and the throttle 22 may be configured by a flow path that defines the notch.

  Hereinafter, an operation when the driving of the mixer drum 1 is stopped will be described. When the ready-mixed concrete is put into the mixer drum 1 and the mixer drum 1 is rotated forward in the direction of arrow B in FIG. 5, the proportional solenoid valve 4 is energized by the controller and is pressurized to be discharged from the hydraulic pump 10 to the supply passage 13. Oil is guided to the second supply / discharge passage 52. In this operating state, when the energization of the proportional solenoid valve 4 is stopped by the controller and the direction switching valve 20 is switched to the neutral position c, the first and second supply / discharge passages 51 and 52 communicate with the supply passage 13. Is cut off, the supply of pressurized hydraulic oil to the hydraulic motor 81 is stopped, and the rotation operation of the hydraulic motor 81 is temporarily stopped.

  When the driving of the mixer drum 1 is stopped, the motor load pressure relief passage 21 is opened as the direction switching valve 20 is switched to the neutral position c, and the supply / discharge ports 85 and 86 of the hydraulic motor 81 are opened. The high pressure side (load pressure side) is communicated with the low pressure side (suction side) of the supply / discharge ports 85 and 86 via the first and second supply / discharge passages 51 and 52 and the motor load pressure relief passage 21.

  When the driving of the mixer drum 1 is stopped, as shown in FIG. 5, when the ready-mixed concrete 9 that has been stirred is unevenly distributed to the side portions in the mixer drum 1, the mixer drum 1 is hydraulically caused by the uneven load of the ready-mixed concrete 9. The motor 81 is driven in the direction of arrow A in FIG. At this time, the load pressure of the hydraulic motor 81 passes from the high pressure side of the first and second supply / discharge passages 51 and 52 to the low pressure side of the first and second supply / discharge passages 51 and 52 through the motor load pressure relief passage 21. Escaped. As a result, the hydraulic motor 81 and the mixer drum 1 are continuously rotated to avoid shaking the mixer drum 1 greatly. Eventually, the ready-mixed concrete 9 moves from the side part in the mixer drum 1 to the lower part, and the rotation of the mixer drum 1 smoothly stops.

  The notch 102A and the notch 103A provide resistance to the flow of hydraulic oil passing through the motor load pressure relief passage 21 as described above, so that the hydraulic motor 81 rotates slowly, and the mixer drum 1 and the mixer car shake. Can be suppressed.

(Second Embodiment)
Next, a second embodiment of the present invention shown in FIG. 3 will be described. This has basically the same configuration as that of the first embodiment, and only different portions will be described. In addition, the same code | symbol is attached | subjected to the same structure part as 1st Embodiment.

  The pump unit 150 includes a motor load pressure relief passage 19 connecting the first and second supply / exhaust passages 51 and 52 of the hydraulic motor 81 and an on-off valve that opens and closes the motor load pressure relief passage 19 as motor load pressure relief means. 31, and the on-off valve 31 opens the motor load pressure relief passage 19 when the drive of the mixer drum 1 is stopped.

  The electromagnetic on-off valve 31 is held at a closed position a that closes the motor load pressure relief passage 19 when not energized, and is switched to an open position b that opens the motor load pressure relief passage 19 when energized. The on-off valve 31 is not limited to this, and the position thereof may be switched via a pilot pressure or a mechanical transmission mechanism.

  The on-off valve 31 includes a throttle 32 that provides resistance to the hydraulic fluid flowing through the motor load pressure relief passage 19 at the open position b.

  Hereinafter, an operation when the driving of the mixer drum 1 is stopped will be described. When the energization of the proportional solenoid valves 4 and 5 is stopped by a controller (not shown) and the direction switching valve 20 is switched to the neutral position c, the first and second supply / discharge passages 51 for the return passage 12 and the supply passage 13 are provided. 52 is cut off, the supply of pressurized hydraulic oil to the hydraulic motor 81 is stopped, and the rotation of the hydraulic motor 81 is temporarily stopped.

  When the driving of the mixer drum 1 is stopped, the on-off valve 31 is switched to the open position b by being energized by the controller. Accordingly, the motor load pressure relief passage 19 is opened, and the first and second supply / discharge passages 51 and 52 of the hydraulic motor 81 are communicated with each other via the motor load pressure relief passage 19.

  When the driving of the mixer drum 1 is stopped, as shown in FIG. 5, when the ready-mixed concrete 9 that has been stirred is unevenly distributed to the side portions in the mixer drum 1, the mixer drum 1 is hydraulically caused by the uneven load of the ready-mixed concrete 9. The motor 81 is driven in the direction of arrow A in FIG. At this time, the load pressure of the hydraulic motor 81 passes from the high pressure side of the first and second supply / discharge passages 51 and 52 to the low pressure side of the first and second supply / discharge passages 51 and 52 through the motor load pressure relief passage 19. Escaped. As a result, the hydraulic motor 81 and the mixer drum 1 are continuously rotated to avoid shaking the mixer drum 1 greatly. Eventually, the ready-mixed concrete 9 moves from the side part in the mixer drum 1 to the lower part, and the rotation of the mixer drum 1 smoothly stops.

  When the throttle 32 gives resistance to the flow of hydraulic oil passing through the motor load pressure relief passage 19, the hydraulic motor 81 is slowly rotated to suppress the shaking of the mixer drum 1 and the mixer truck. Since the on-off valve 31 is provided separately from the direction switching valve 20, the degree of freedom for setting the shape of the throttle 32 and the like is increased.

(Third embodiment)
Next, a third embodiment of the present invention shown in FIG. 4 will be described. This has basically the same configuration as that of the second embodiment, and only different portions will be described. In addition, the same code | symbol is attached | subjected to the same structure part as 2nd Embodiment.

  The pump unit 250 has a motor load pressure relief means for releasing the load pressure of the hydraulic motor 81 through the first and second supply / discharge passages 51 and 52 to the tank 90 side (low pressure side of the working fluid pressure source) as a motor load pressure release means. A passage 29 and an on-off valve 28 for opening and closing the motor load pressure relief passage 29 are provided, and the on-off valve 28 opens the motor load pressure relief passage 29 when the driving of the mixer drum 1 is stopped.

  One end of the motor load pressure relief passage 29 is communicated with the high pressure side (load pressure side) of the first and second supply / exhaust passages 51 and 52 via the high pressure selection valve 16, and the opening / closing valve 28 is interposed in the middle thereof. The other end communicates with the tank 90. Both the motor load pressure relief passage 29 and the first pilot pressure passage 41 are connected to the common high pressure selection valve 16 via the on-off valve 28. The on-off valve 28 operates as a direction switching valve that selectively connects one of the motor load pressure relief passage 29 and the first pilot pressure passage 41 to the high pressure selection valve 16.

  The electromagnetic on-off valve 28 is held at a position a for closing the motor load pressure relief passage 29 and opening the first pilot pressure passage 41 when not energized, and closing the first pilot pressure passage 41 and energizing the motor load pressure when energized. The position is switched to the position b where the passage 29 is opened. The on-off valve 28 is not limited to this, and the position thereof may be switched through a pilot pressure or a mechanical transmission mechanism.

  The on-off valve 28 includes a throttle 27 that provides resistance to the hydraulic fluid flowing through the motor load pressure relief passage 29 at the position b.

  Hereinafter, an operation when the driving of the mixer drum 1 is stopped will be described. As the proportional solenoid valves 4 and 5 are de-energized by the controller and the direction switching valve 20 is switched to the neutral position c, the communication of the first and second supply / discharge passages 51 and 52 to the supply passage 13 is cut off. The supply of the pressurized hydraulic oil to the hydraulic motor 81 is stopped, and the rotational operation of the hydraulic motor 81 is temporarily stopped.

  When the driving of the mixer drum 1 is stopped, the on-off valve 28 is switched to the position b by being energized by the controller, and opens the motor load pressure relief passage 29. At this time, the high pressure selection valve 16 communicates one of the first and second supply / discharge passages 51, 52 to which the load pressure of the hydraulic motor 81 is guided to the motor load pressure relief passage 29. Thus, one of the first and second supply / discharge passages 51 and 52 through which the load pressure of the hydraulic motor 81 is guided is communicated with the tank 90 through the motor load pressure release passage 29.

  When the driving of the mixer drum 1 is stopped, as shown in FIG. 5, when the ready-mixed concrete 9 that has been stirred is unevenly distributed to the side portions in the mixer drum 1, the mixer drum 1 is hydraulically caused by the uneven load of the ready-mixed concrete 9. The motor 81 is driven in the direction of arrow A in FIG. At this time, the load pressure of the hydraulic motor 81 is released from the high pressure side of the first and second supply / discharge passages 51 and 52 to the tank 90 side through the motor load pressure release passage 29. As a result, the hydraulic motor 81 and the mixer drum 1 are continuously rotated to avoid shaking the mixer drum 1 greatly. Eventually, the ready-mixed concrete 9 moves from the side part in the mixer drum 1 to the lower part, and the rotation of the mixer drum 1 smoothly stops.

  When the throttle 27 gives resistance to the flow of the hydraulic oil passing through the motor load pressure relief passage 29, the hydraulic motor 81 is slowly rotated and the shaking of the mixer drum 1 and the mixer truck can be suppressed. Since the on-off valve 28 is provided separately from the direction switching valve 20, the degree of freedom for setting the shape of the throttle 27 and the like is increased.

  The high pressure selection valve 16 guides the pilot pressure to the load sensing valve 40 through the first pilot pressure passage 41 when the mixer drum 1 is driven, while the load pressure of the hydraulic motor 81 is released from the motor load pressure passage when the mixer drum 1 is stopped. It works to escape to 90 through 29 to the tank. Therefore, the pump unit 250 does not need to include two high-pressure selection valves corresponding to the first pilot pressure passage 41 and the motor load pressure relief passage 29, and the structure thereof can be prevented from becoming complicated.

  According to the above embodiment, there exists an effect shown below.

  (A) The drum drum driving device of the present embodiment includes a positive displacement fluid pressure motor (hydraulic motor) 81 that rotationally drives the mixer drum 1, supply / discharge passages 51, 52 that supply and discharge the working fluid to the fluid pressure motor 81, When the instruction to stop the driving of the mixer drum 1 is issued and the driving of the fluid pressure motor 81 is stopped, the load pressure of the working fluid generated in the volume chamber of the fluid pressure motor 81 is supplied through the supply / discharge passages 51 and 52. It is set as the structure provided with the motor load pressure relief means to escape to the low voltage | pressure side (refer FIGS. 1-5).

  According to the above configuration, when the driving of the mixer drum 1 is stopped, the load pressure of the fluid pressure motor 81 is lowered to the low pressure side through the supply / discharge passages 51 and 52 in a situation where the torque due to the unbalanced load of the mixer drum 1 acts on the mixer drum 1. By being escaped, the fluid pressure motor 81 continuously rotates in the opposite direction to that before driving, and the mixer drum 1 is smoothly stopped.

  Thereby, after the driving of the mixer drum 1 is stopped, the fluid pressure motor 81 is prevented from rotating discontinuously due to internal leakage of the working fluid, and the mixer drum 1 is prevented from being shaken.

  (A) The supply / discharge passages 51 and 52 are constituted by first and second supply / discharge passages 51 and 52 for supplying and discharging the working fluid to and from the fluid pressure motor 81. The motor load pressure release means of the present embodiment is the first , The motor load pressure relief passage 21 connecting the second supply / discharge passages 51, 52 and the pressurized working fluid supplied from the working fluid pressure source (pump unit 50) are supplied to the first and second supply / discharge passages 51, 52. A direction switching valve 20 that selectively leads to one side, and the direction switching valve 20 opens the motor load pressure relief passage 21 when the supply of the pressurized working fluid to the fluid pressure motor 81 is stopped. Thus, the load pressure of the fluid pressure motor 81 is released from one of the first and second supply / discharge passages 51 and 52 to the other of the first and second supply / discharge passages 51 and 52 (see FIGS. 1 and 2).

  According to the above configuration, when the driving of the mixer drum 1 is stopped, the motor load pressure relief passage 21 is opened as the direction switching valve 20 stops the supply of the pressurized working fluid to the fluid pressure motor 81. To do. As a result, in a situation where torque due to the unbalanced load of the mixer drum 1 acts on the mixer drum 1, the load pressure of the fluid pressure motor 81 is released through the one of the first and second supply / exhaust passages 51, 52 to the other that becomes the low pressure side. The mixer drum 1 stops smoothly.

  (C) The direction switching valve 20 of the present embodiment includes a valve housing hole 110 that slidably houses the spool 100, and the valve housing hole 110 is supplied from a working fluid pressure source (pump unit 50). A supply passage 13 for introducing a pressurized working fluid, first and second supply / discharge passages 51 and 52, and a return passage 12 for returning the working fluid to the low pressure side (tank 90 side) of the working fluid pressure source (pump unit 50). , And the spool 100 is switched to the neutral position c where the communication of the first and second supply / discharge passages 51 and 52 with respect to the supply passage 13 is cut off. The motor load pressure relief passage 21 that connects the supply / discharge passages 51 and 52 is configured (see FIG. 2).

  According to the above configuration, it is not necessary to form a dedicated passage that constitutes the motor load pressure relief passage 21 in the housing 24 in which the direction switching valve 20 is accommodated, and the cost of the product can be suppressed.

  (D) As a motor load pressure relief means, a motor load pressure relief passage 19 connecting the first and second supply / exhaust passages 51 and 52 and an opening / closing valve 31 for opening and closing the motor load pressure relief passage 19 are provided. When the driving of the mixer drum 1 is stopped, the on-off valve 31 opens the motor load pressure relief passage 19 (see FIG. 3).

  According to the above configuration, when the drive of the mixer drum 1 is stopped, the on-off valve 31 opens the motor load pressure relief passage 19. As a result, in a situation where torque due to the unbalanced load of the mixer drum 1 acts on the mixer drum 1, the load pressure of the fluid pressure motor 81 is released through the one of the first and second supply / exhaust passages 51, 52 to the other that becomes the low pressure side. The mixer drum 1 stops smoothly.

  (E) As a motor load pressure release means, a motor load pressure release passage 29 for releasing the load pressure of the fluid pressure motor 81 to the tank 90 side through the high pressure side of the first and second supply / discharge passages 51 and 52, and the motor load pressure And an opening / closing valve 28 for opening / closing the relief passage 29, and when the driving of the mixer drum 1 is stopped, the opening / closing valve 28 opens the motor load pressure relief passage 29 (see FIG. 4).

  According to the above configuration, when the driving of the mixer drum 1 is stopped, the on-off valve 31 opens the motor load pressure relief passage 29. As a result, in a situation where torque due to the unbalanced load of the mixer drum 1 acts on the mixer drum 1, the load pressure of the fluid pressure motor 81 escapes to the tank 90 side, which is the low pressure side, through one of the first and second supply / discharge passages 51 and 52. The mixer drum 1 stops smoothly.

  (F) The motor load pressure relief passages 19, 21, and 29 are provided with throttles 22, 27, and 32 that provide resistance to the working fluid (see FIGS. 1 to 5).

  According to the above configuration, the throttle 22, 27, 32 imparts resistance to the flow of the working fluid that passes through the motor load pressure relief passages 19, 21, 29, so that the fluid pressure motor 81 rotates slowly, The shaking of the mixer drum 1 can be suppressed.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

DESCRIPTION OF SYMBOLS 1 Mixer drum 12 Return path 13 Supply path 19, 21, 29 Motor load pressure relief path 20 Direction switching valve 22, 27, 32 Throttle 28, 31 On-off valve 50, 150, 250 Pump unit (working fluid pressure source)
51 First supply / discharge passage (supply / discharge passage)
52 Second supply / discharge passage (supply / discharge passage)
81 Hydraulic motor (fluid pressure motor)
82 Relief valve 90 Tank 100 Spool 110 Valve accommodation hole

Claims (6)

A mixer drum driving device in which the mixer drum is rotationally driven by a positive displacement fluid pressure motor;
A supply / discharge passage for supplying and discharging the working fluid to the fluid pressure motor;
A motor that releases the load pressure of the working fluid generated in the volume chamber of the fluid pressure motor to the low pressure side through the supply / discharge passage when the instruction to stop the drive of the mixer drum is issued and the drive of the fluid pressure motor is stopped. A mixer drum drive device comprising load pressure relief means. The supply / discharge passage is constituted by first and second supply / discharge passages that supply and discharge the working fluid to and from the fluid pressure motor,
The motor load pressure relief means is
A motor load pressure relief passage connecting the first and second supply / discharge passages;
A direction switching valve that selectively guides the pressurized working fluid supplied from the working fluid pressure source to one of the first and second supply / discharge passages,
The directional control valve opens the motor load pressure relief passage as the supply of the pressurized working fluid to the fluid pressure motor is stopped, thereby opening the load pressure of the fluid pressure motor to the first and second supply pressures. 2. The mixer drum driving device according to claim 1, wherein one of the discharge passages escapes to the other of the first and second supply / discharge passages. The direction switching valve includes a valve accommodating hole for slidably accommodating the spool,
In the valve housing hole, a supply passage for guiding a pressurized working fluid supplied from the working fluid pressure source, the first and second supply / discharge passages, and the working fluid are returned to the low pressure side of the working fluid pressure source. Are connected to the return path,
As the spool is switched to a neutral position where communication between the first and second supply / discharge passages with respect to the supply passage is blocked, the return passage communicates between the first and second supply / discharge passages. 3. The mixer drum driving device according to claim 2, wherein a motor load pressure relief passage is formed. As the motor load pressure relief means,
A motor load pressure relief passage connecting the first and second supply / discharge passages;
An on-off valve for opening and closing the motor load pressure relief passage,
The mixer drum driving apparatus according to claim 1, wherein when the driving of the mixer drum is stopped, the on-off valve opens the motor load pressure relief passage. As the motor load pressure relief means,
A motor load pressure relief passage for releasing the load pressure of the fluid pressure motor to the tank side through the high pressure side of the first and second supply / discharge passages;
An on-off valve for opening and closing the motor load pressure relief passage,
The mixer drum driving apparatus according to claim 1, wherein when the driving of the mixer drum is stopped, the on-off valve opens the motor load pressure relief passage.   The mixer drum driving device according to any one of claims 2 to 5, further comprising a throttle for imparting resistance to the working fluid flowing through the motor load pressure relief passage.

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