JP2016118153A - Work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To configure a work vehicle that smoothly switches a rotary operation of a cooling fan without causing a shock or excessive pressure fluctuation at a switch-over between normal rotation and reverse rotation of a hydraulic motor that drives the cooling fan.SOLUTION: The work vehicle is formed with: a relief flow passage having a relief valve 55 for discharging hydraulic oil into a hydraulic oil tank 47 when pressure of one of paired motor flow passages 51 of the hydraulic motor M is raised; and a suction flow passage having a suctioning check valve 59 for suctioning the hydraulic oil from the hydraulic oil tank 47 into the motor flow passages 51 when the pressure of one of paired motor flow passages 51 reaches a negative pressure state.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a work vehicle in which a cooling fan for supplying cooling air to a radiator is driven by a hydraulic motor.

  Taking a combine as an example of a work vehicle, when air is sucked by a cooling fan during work, dust such as straw adsorbs to the dust proof net of the radiator, and cooling performance may deteriorate. In order to suppress such an inconvenience, Patent Document 1 discloses a technique in which a cooling fan is reversed at a set time interval to blow off dust such as straw attached to a dust-proof net.

  In Patent Document 1, an electromagnetic valve that controls hydraulic oil supplied from a hydraulic pump to a hydraulic motor is provided. The hydraulic valve is operated by switching the flow of hydraulic oil supplied to the hydraulic motor by operating the electromagnetic valve every set time. A technique for switching the rotation direction of a motor is shown.

  Patent Document 2 discloses a technique for switching between normal rotation and reverse rotation of a cooling fan by operating a switching valve, which is different from the purpose of blowing dust such as straw. In Patent Document 2, a pair of flow paths of a hydraulic motor are provided via an orifice between a forward rotation position (forward rotation position) where forward rotation is performed in a switching valve and a reverse rotation position (reverse rotation position) where reverse rotation is performed. A rotation free position (free rotation position) for communication is shown.

JP-A-8-144755 Japanese Patent Laid-Open No. 2004-251124

  Taking the flow path configuration of Patent Document 1 as an example, if the solenoid valve is a two-position switching type of a forward rotation position and a reverse rotation position, the hydraulic oil supply direction is switched by operating the electromagnetic valve. In this case, immediately after this switching, the hydraulic motor rotates due to the inertia of the cooling fan, and the hydraulic motor functions like a hydraulic pump, so that the fluid is supplied to the pair of flow paths for supplying and discharging the hydraulic oil to and from the hydraulic motor. Invite a phenomenon of continuous flow.

  In other words, when switching the position of the solenoid valve, the supply and discharge of hydraulic fluid to and from the pair of flow paths of the hydraulic motor is completely stopped at the intermediate position between both positions, and not only a large braking force acts on the hydraulic motor, but also a cooling fan The hydraulic motor rotates due to the inertia. For this reason, it is considered that not only surge pressure is generated in one of the pair of flow paths, but also the other flow path becomes negative pressure and the hydraulic motor is damaged or hydraulic oil leaks.

  On the other hand, when the switching valve for controlling the rotation of the hydraulic motor is operated between the forward rotation position and the reverse rotation position as shown in Patent Document 2, when passing through the rotation free position, Since hydraulic fluid is allowed to flow between a pair of flow paths of the hydraulic motor, it is possible to suppress the generation of surge pressure and negative pressure generated in the flow paths and to switch the rotation direction of the hydraulic motor. .

  However, even with the switching valve disclosed in Patent Document 2, when the switching between the forward rotation position and the reverse rotation position is performed at a high speed, the rotation free position hardly functions and there is room for improvement. is there.

  An object of the present invention is to constitute a work vehicle that does not cause a shock or an excessive change in oil pressure even when a hydraulic motor that drives a cooling fan is switched between forward rotation and reverse rotation.

A feature of the present invention is that a radiator that cools cooling water of an engine, a dust net disposed outside the body of the radiator from the radiator, a cooling fan that is disposed inside the body of the radiator and supplies cooling air to the radiator, A hydraulic motor for driving the cooling fan,
A hydraulic pump driven by the engine, and a rotation control valve for controlling hydraulic oil supplied from the hydraulic pump to the hydraulic motor;
The hydraulic motor is configured to rotate forward when hydraulic oil flows from one of the pair of motor flow paths to the other, and reverse when hydraulic oil flows in the opposite direction. Select the motor flow path and supply hydraulic oil.
A communication channel is provided between the pair of motor channels and the hydraulic oil tank.

For example, when the valve shown in Patent Document 1 is switched between the forward rotation position and the reverse rotation position, the supply and discharge of the hydraulic oil to and from the pair of flow paths of the hydraulic pump completely stops in the middle of each position. A situation is created. Even in such a situation, since the hydraulic motor continuously rotates due to inertia, the pressure of one of the pair of flow paths increases greatly and the other becomes a negative pressure.
On the other hand, according to the above-described characteristic configuration, when the rotation direction of the hydraulic motor is switched by operating the rotation control valve, the hydraulic oil in the flow path in which the pressure has increased among the pair of motor flow paths is passed through the communication flow path. Thus, the hydraulic oil in the hydraulic oil tank can be supplied to the flow path that is sent to the hydraulic oil tank and has a negative pressure. Therefore, even when the hydraulic motor that drives the cooling fan is switched between forward rotation and reverse rotation, a work vehicle that does not cause a shock or an excessive change in oil pressure is configured.

  In the present invention, the communication flow path may be configured as a relief flow path including a relief valve that is opened by pressure increase of the motor flow path and discharges hydraulic oil to the hydraulic oil tank.

  According to this, when the rotation direction of the hydraulic motor is switched by the control of the rotation control valve and the pressure in one motor flow path rises, the relief valve discharges the hydraulic oil in the motor flow path to the hydraulic oil tank and pressurizes The rise can be suppressed.

  The present invention provides a relief check in which the relief passage allows only a flow in a discharge direction of hydraulic oil from the first connection passage and the first connection passage connected to each of the pair of motor passages. A valve and a single merging channel for joining the hydraulic oil that has flowed through these relief check valves may be provided, and a relief valve may be connected to the merging channel.

  According to this, even if any pressure of the pair of motor flow paths increases, if the pressure rises above the relief pressure, the hydraulic oil of the motor flow path is removed from the first connection flow path by a single relief valve. It becomes possible to discharge through. Further, since the relief check valve is provided, it is possible to avoid the disadvantage that hydraulic oil flows from one flow path to the other flow path during normal operation of the hydraulic motor.

  In the present invention, the communication flow path is a suction flow path provided with a check valve for suction that opens when the motor flow path becomes negative pressure and supplies the hydraulic oil in the hydraulic oil tank to the motor flow path. It may be configured.

  According to this, when the rotation direction of the hydraulic motor is switched by the control of the rotation control valve and one of the motor flow paths becomes negative pressure, the suction check valve is opened and the hydraulic oil in the hydraulic oil tank flows through the motor flow. The negative pressure can be eliminated by supplying to the road.

  According to the present invention, the suction flow path is connected to each of the suction flow path communicating with the hydraulic oil tank, the branch flow path for branching and feeding the hydraulic oil sucked in the suction flow path, and the pair of motor flow paths. And a second connection flow path to be connected, and the check valve for suction operates from the branch flow path to the second connection flow path at a position connecting the branch flow path and the second connection flow path. You may be provided in the state which accept | permits the flow of oil.

  According to this, even if any of the pair of flow paths becomes negative pressure, the suction check valve of the second connection flow path connected to the flow path is opened, so that the hydraulic oil tank is opened with respect to the flow path. It becomes possible to supply the hydraulic oil. Further, since the check valve for suction is provided, it is possible to avoid the disadvantage that hydraulic oil flows from one flow path to the other flow path during normal operation of the hydraulic motor.

In the present invention, the axis of the output shaft of the engine is set in a posture along the left-right direction of the fuselage, and the cooling fan and the radiator are disposed outside the fuselage from the engine,
The output shaft is disposed on the opposite side of the radiator in the left-right direction of the airframe, and a counter shaft that is rotated by a driving force from the output shaft is disposed in a posture along the left-right direction of the airframe. The driving force from the end position may be transmitted to the hydraulic pump.

  According to this, even if the output shaft of the engine is disposed on the opposite side of the radiator in the left-right direction of the machine body, the driving force of the output shaft can be transmitted to the hydraulic pump via the counter shaft. Further, according to this configuration, since the hydraulic pump and the hydraulic motor can be disposed close to each other, it is possible to shorten the flow path length between the hydraulic pump and the hydraulic motor.

  The present invention may include a travel transmission mechanism that transmits the driving force of the counter shaft to the travel transmission case of the airframe.

  According to this, the driving force of the countershaft can be transmitted to the traveling transmission case via the traveling transmission mechanism, and the aircraft can be traveled.

  In the present invention, the cooling fan and the hydraulic motor may be arranged above a center position in the vertical direction of the engine.

  According to this, by arranging the radiator at a relatively high position, it is possible to suppress the inconvenience that dust during operation is sucked into the radiator.

  In the present invention, the radiator and the hydraulic motor may be supported by a radiator frame standing on the machine body, and the hydraulic pump may be disposed at a position adjacent to the radiator frame.

  According to this, since the radiator and the hydraulic motor are supported by the radiator frame, the relative positional relationship between the radiator and the hydraulic motor can be maintained. In addition, the hydraulic pump can be disposed at a position close to the hydraulic motor, and it is easy to provide a flow path between the hydraulic pump and the hydraulic motor.

  In the present invention, the hydraulic oil tank may be disposed in the vicinity of a radiator frame that supports the radiator.

  According to this, it becomes possible to shorten the flow path for supplying the hydraulic oil in the hydraulic oil tank to the hydraulic pump.

1 is an overall side view of a corn harvester. It is a top view which shows the transmission structure of a corn harvester. It is a top view which shows an engine, a radiator, and a cooling fan. It is a longitudinal section showing an engine, a radiator, and a cooling fan. It is a perspective view which shows a radiator frame and a cooling fan. It is a hydraulic circuit diagram which drives a hydraulic motor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Basic configuration]
FIG. 1 shows a wheel-running corn harvester as an example of a work vehicle. The corn harvester has a traveling machine body F that travels with a pair of left and right front wheels 1 and a pair of left and right rear wheels 2, and includes a cabin 3 at a front position of the traveling machine body F.

  As shown in the figure, the traveling machine body F performs the harvesting operation while traveling in the forward direction X. In the traveling machine body F, the end portion in the forward direction X is the front end. Further, in the traveling machine body F, the end in the direction opposite to the front direction X is the rear end. Further, the worker's right side is the right side of the traveling machine body F and the worker's left side is the left side of the traveling machine body F in a posture in which the worker is directed in the forward direction X.

  In the present invention, the working vehicle can be applied to a corn harvester that does not include a skinning device 15 described later, and can be applied to all working vehicles such as a wheel-type combine.

  A harvesting section A is provided at the front end of the traveling machine body F so as to be movable up and down, and the harvested product (corn in a state of being wrapped in foliage) harvested by the harvesting section A is transported upward and rearward from the front end of the traveling machine body F to the center. The transport device 5 is provided. The transport device 5 is provided with a blower 6 that blows off some of the leaves and stems mixed in the transported crop. At the central position of the traveling machine body F, a crop processing unit B that removes foliage from the crop supplied by the transport device 5 and a crop tank that stores corn from which the foliage has been removed by the crop processing unit B are stored. 7. Further, a residue processing device C is provided below the traveling machine body F and between the front wheel 1 and the rear wheel 2.

  The traveling machine body F includes a pair of left and right machine body frames 8 extending in the front-rear direction and a cabin frame 9 at the front position. The engine E is supported at a central position in the front-rear direction of the body frame 8, and a traveling transmission case 11 that drives the front wheels 1 is provided at a front position of the body frame 8. The rear wheel 2 is configured to be freely steerable. Further, the traveling machine body F includes a transmission system that transmits the driving force from the engine E to the traveling transmission case 11 or the harvesting part A, the harvested part processing part B, and the like. Details of this transmission system will be described later.

  The cabin frame 9 is disposed at a position higher than the body frame 8 and supports the cabin 3. The cabin 3 has a general configuration including a windshield, left and right doors, and a roof, and includes a driver seat in which a work vehicle is seated. In the vicinity of the driver's seat, a steering hole, levers for controlling traveling of the traveling machine body, or levers for controlling work are arranged.

  The harvesting part A is provided with a plurality of dividers 12 at the tip position, and is provided with a plurality of conveying mechanisms 13 for conveying the harvested product while separating the harvest from the cereal grains introduced at the middle positions of these dividers 12. An auger 14 that rotates about an axial core in a lateral orientation is provided to transfer the harvested product to a central position in the left-right direction. The transport device 5 has a belt conveyor-shaped transport structure inside a duct-shaped case, and supplies the harvested product from the auger 14 to the harvested product processing section B.

  The harvest processing unit B is arranged in a positional relationship in which the peeling device 15, the swing sorting device 16, and the collection container 17 are vertically stacked. In the harvest processing unit B, the skinning device 15 removes the foliage from the harvest supplied from the transport device 5 and feeds the corn from which the foliage has been removed to the harvest tank 7. In the harvested product processing section B, the seed leaves separated by the skinning device 15 and a part of the seed grains separated from the corn are subjected to rocking and sorting by the rocking and sorting device 16, the leaf leaves are discharged out of the machine body, It is recovered in the recovery container 17.

  The residue processing apparatus C includes a plurality of crushing blades 18A with respect to the processing shaft 18 in the lateral orientation, and has a configuration in which these are accommodated in a processing case 19 that opens downward. With this configuration, the crushing blade 18 </ b> A shreds and crushes the residue of the farm scene and diffuses it into the soil by the drive rotation of the processing shaft 18.

[Transmission configuration]
As shown in FIGS. 2 to 4, the engine E has the crankshaft set in a posture along the left-right direction of the traveling machine body F, and the output shaft to which the driving force from the crankshaft is transmitted is set on the side opposite to the radiator 31. The output shaft is provided with a plurality of engine output pulleys 21.

  As shown in FIGS. 2 and 3, a counter shaft 22 having a posture along the left-right direction of the airframe is disposed on the front side of the airframe with respect to the engine E. Is provided with a belt-type first traveling transmission mechanism 22a. Further, a belt-type second traveling transmission mechanism 22 b that transmits a driving force from the outer end position of the counter shaft 22 to the input shaft 11 a of the traveling transmission case 11 is provided.

  The traveling transmission case 11 includes a hydrostatic continuously variable transmission that shifts the driving force transmitted from the engine E via the second traveling transmission mechanism 22b and transmits it to the left and right front wheels 1. The hydrostatic continuously variable transmission is configured such that the forward travel speed and the reverse travel speed can be adjusted steplessly, and the travel speed can be changed by performing a speed change operation from the inside of the cabin 3.

  As shown in FIG. 2, an intermediate shaft 23 parallel to the output shaft of the engine E is provided. Between the engine output pulley 21 and the intermediate shaft 23, a belt tension type of intermittent driving force to the intermediate shaft 23 is provided. A working clutch 24 is provided. As a transmission configuration for transmitting the driving force of the intermediate shaft 23 to the harvesting section A, a belt-type first harvesting transmission mechanism 25a and a chain-type second harvesting transmission mechanism 25b are provided. In the harvesting part A, a portion where the driving force from the second harvesting transmission mechanism 25b is transmitted is provided with a torque limiter TL.

  Further, as a transmission configuration for transmitting the driving force of the intermediate shaft 23 to the harvested processing unit B, a belt-type first processing transmission mechanism 26 a that transmits the driving force of the intermediate shaft 23 to the driving shaft 6 a of the blower 6 is provided. Furthermore, a chain-type second processing transmission mechanism 26b that transmits the driving force from the drive shaft 6a of the blower 6 to the peeling device 15, and a chain-type third processing transmission mechanism 26c that transmits this driving force to the swing sorting device 16; It has. A torque limiter TL is provided between the second processing transmission mechanism 26b and the third processing transmission mechanism 26c.

  The conveying device 5 is configured by housing a conveyor belt having a structure in which a shaft body is provided at a start position and an end position in the conveying direction, and a blade or the like is provided on a chain wound around these shaft bodies. . A discharge device 27 having a pair of rotating members that sandwich and discharge a part of a leaf, stem, or the like mixed in the processed material conveyed by the conveyance device 5 is provided at the terminal position of the conveyance device.

  In the transport device 5, a shaft body at the transport end position is configured as a transport input shaft 5a, and a rotation shaft that drives and rotates a rotating member of the discharge device 27 is configured as a discharge device input shaft 27a. The discharge device input shaft 27a On the other hand, a chain-type conveyance transmission mechanism 28 that transmits a driving force from the drive shaft 6a of the blower 6 is provided.

  Further, in order to transmit the driving force of the intermediate shaft 23 to the processing shaft 18 of the residue processing apparatus C, a residue processing transmission mechanism 29 using a gear and a belt is provided.

[Harvesting form]
From such a transmission configuration, in the corn harvester, the driving force of the engine E can be transmitted from the traveling transmission case 11 to the left and right front wheels 1 by the operation of the operator inside the cabin 3 to cause the traveling machine body F to travel. Become.

  Also, by operating the operation clutch 24, the driving force of the engine E is transmitted to the harvesting section A, the transport device 5, the blower 6, the harvested product processing section B, and the residue processing apparatus C, and the harvesting operation is performed. Is possible. In this harvesting operation, a harvested product (corn wrapped in foliage) is harvested in the harvesting unit A, and the harvested product is supplied to the harvested product processing unit B by the transport device 5. When the harvested product is transported by the transport device 5, a part of the leaves and stems mixed in the harvested product is sent out by the discharge device 27 and discharged outside the machine body by the wind pressure of the blower 6.

  In the harvest processing unit B, the foliage is removed from the harvest by the skinning device 15, the corn from which the foliage has been removed is sent to the harvest tank 7, and the foliage is discharged to the outside of the machine body. In addition, some seed grains separated from the corn in the skinning device 15 are rocked and sorted by the rocking and sorting device 16 and then collected in the collection container 17. Moreover, the cereal residue left in the field scene is processed by the residue processing apparatus C in a form that is crushed and diffused into the soil.

[Radiator]
As shown in FIGS. 3 to 5, a radiator 31 and an intake case 32 are supported on a radiator frame 40 provided on the right side of the body frame 8. The radiator 31 is disposed outside the body of the engine E, and the vertical center position thereof is set higher than the vertical center position of the engine E. In addition, a dust-proof net 33 is provided on the outer surface of the intake case 32, a cooling fan 34 is disposed on the back side of the radiator 31, and a fan shroud 35 is provided on the back side of the radiator 31 at a position surrounding the cooling fan 34. The radiator 31 is connected to the engine E via a pair of radiator hoses 36 so that the cooling water from the engine E is cooled and returned to the engine E.

  Although not shown in the drawing, an oil cooler that radiates hydraulic oil and a capacitor that radiates refrigerant are accommodated in the intake case 32.

  The radiator frame 40 includes an auxiliary frame 41 projecting outward from the machine body frame 8, a pair of front and rear columnar frames 42 erected on the upper surface of the auxiliary frame 41, and upper ends of the pair of columnar frames 42. And an upper connecting frame 43 in a front-and-back orientation that is connected to the front and rear. The radiator frame 40 also includes a pair of auxiliary upper frames 44 that extend inward from the two locations of the middle position in the front-rear direction of the upper connecting frame 43 and the position on the front end side.

  Further, the radiator frame 40 includes an auxiliary support frame 45 on the inner side of the body with reference to a support frame 42 on the front side of the machine body. An auxiliary upper frame 44 on the front side of the machine body is connected to the upper end of the auxiliary support frame 45. Yes. The extending ends of the horizontal frame 45a extending rearward from the intermediate position of the auxiliary support frame 45 and the vertical frame 44a extending downward from the auxiliary upper frame 44 at the central position are connected to each other. A hydraulic motor M is supported on the connecting portion via a motor bracket 37, and a cooling fan 34 is connected to the output shaft of the hydraulic motor M.

  The cooling fan 34 is driven in the forward direction in which the cooling air is sucked by the hydraulic motor M and in the reverse direction in which the cooling air is discharged, and a hydraulic pump P that supplies hydraulic oil to the hydraulic motor M is on the front side. It is arranged in the vicinity of the columnar frame 42. The hydraulic pump P is supported on the body frame 8 via a pump bracket 38, and the drive shaft of the hydraulic pump P and the counter shaft 22 are connected by a flexible joint 39 such as a rubber coupling.

  In order to arrange the axis of the drive shaft of the hydraulic pump P and the axis of the counter shaft 22 on the same axis, a long hole is formed in the support member of the pump bracket 38 or the body frame 8, and a bolt is inserted into this. This makes it possible to adjust the position in the longitudinal direction of the aircraft. Further, the position adjustment in the vertical direction is performed by inserting a shim between the pump bracket 38 and the support member of the body frame 8.

[Control structure of hydraulic motor]
In this corn harvester, the lubricating oil stored in the traveling transmission case 11 is used as hydraulic oil, and the traveling transmission case 11 is also used as a main tank for hydraulic oil. Further, a hydraulic oil tank 47, a valve unit VU, and a battery having a capacity smaller than that of the main tank are disposed in the body frame 8 in the vicinity of the radiator frame 40. FIG. 6 shows a hydraulic circuit including the hydraulic pump P, the hydraulic motor M, and the valve unit VU.

  The hydraulic oil tank 47 is configured so that a constant amount of hydraulic oil is always stored, and the hydraulic oil flows between the hydraulic oil tank and the main tank (traveling transmission case 11). Further, a flow path through which the hydraulic pump P sucks the hydraulic oil in the hydraulic oil tank 47, a flow path to supply the hydraulic oil from the hydraulic pump P to the valve unit VU, and the hydraulic oil from the valve unit VU to the hydraulic oil tank 47. A flow path for discharging is formed. Further, a pair of motor flow paths 51 are formed between the valve unit VU and the hydraulic pump P. These flow paths are constituted by dedicated pipes.

  The valve unit VU includes a rotation control valve V. The rotation control valve V is configured as an electromagnetic valve including a spool that can be switched between a forward rotation position and a reverse rotation position, and an electromagnetic solenoid that operates the spool. The traveling machine body F includes a control device 48 that outputs a control signal to the electromagnetic valve. The rotation control valve V maintains the forward rotation position in a state where electric power is not supplied to the electromagnetic solenoid, and is set to the reverse rotation position when electric power is supplied to the electromagnetic solenoid. The control device 48 includes a control circuit having a microprocessor, a DSP, and the like, and software, and controls the rotation direction of the cooling fan 34 by operating the rotation control valve V.

  The control device 48 performs control for driving the cooling fan 34 in the forward rotation direction for sucking the cooling air, for example, for 3 minutes, and performs control for driving the cooling fan 34 in the reverse rotation direction for discharging the cooling air, for 10 seconds. Repeat the above control. In particular, when the spool of the rotation control valve V is operated to switch the rotation direction of the hydraulic motor M, the hydraulic oil is hardly supplied to the hydraulic motor M between the forward rotation position and the reverse rotation position. Appears.

  When the work clutch 24 is in the disengaged state, the cooling fan 34 is driven to rotate forward, and the cooling fan 34 is switched between forward rotation and reverse rotation only when the work clutch 24 is engaged and operated. Although the control mode is set, the switching between the forward rotation and the reverse rotation may be performed regardless of the state of the work clutch 24.

  If the hydraulic oil is not supplied to or discharged from the hydraulic motor M at an intermediate position in this way, a large braking force is applied to the hydraulic motor M and smooth deceleration is not performed, leading to inconveniences that cause vibration and impact. It was a thing. In particular, when the rotation direction of the cooling fan 34 is switched, the hydraulic motor M tends to rotate with inertia, so that surge pressure is applied to one of the pair of motor flow paths 51 through which hydraulic oil is supplied to and discharged from the hydraulic motor M. Occurred (excessive pressure is applied), and negative pressure is generated on the other side, leading to leakage of hydraulic oil from the flow path or damage to the flow path.

  In order to eliminate this inconvenience, the valve unit VU shown in FIG. 6 includes a pressure difference suppression circuit. This pressure difference suppression circuit includes a relief flow path configured as a communication flow path between a pair of motor flow paths 51 through which hydraulic oil is supplied and discharged in the hydraulic motor M and the hydraulic oil tank 47, and a suction flow path. I have.

  The relief flow path includes a first connection flow path 52 connected to the pair of motor flow paths 51, a relief check valve 53 on the downstream side of the first connection flow path 52, and a pair of relief check valves 53. A merging channel 54 for merging the hydraulic oil and a relief valve 55 connected to the merging channel 54 are provided. In this relief flow path, the hydraulic oil in the motor flow path 51 is discharged from the relief valve 55 to the hydraulic oil tank 47 via the tank flow path 56 only when the pressure in the motor flow path 51 rises. Also. The direction of the relief check valve 53 is set so as to prevent the flow of hydraulic oil in the reverse direction.

  The suction flow path includes a tank flow path 56 (an example of a suction flow path, which is also used as a discharge system for hydraulic oil from the relief valve 55) communicating with the hydraulic oil tank 47, and a branch flow branched from the tank flow path 56. A suction check valve 59 is provided at a position connecting the passage 57, the second connection passage 58 connected to the pair of motor passages 51, and the branch passage 57 and the second connection passage 58. In this suction flow path, the direction of the suction check valve 59 is set so that the hydraulic oil in the hydraulic oil tank 47 can be sucked into the motor flow path 51 only when the pressure of the motor flow path 51 is reduced. Yes.

  As described above, the communication flow path includes the first connection flow path 52 that constitutes the relief flow path, the relief check valve 53, the merge flow path 54, and the relief valve 55, and the tank that constitutes the suction flow path. A flow path 56, a branch flow path 57, a second connection flow path 58, and a suction check valve 59 are provided.

  In this hydraulic circuit, the valve unit VU may be provided with only one of the relief flow path and the suction flow path. Moreover, you may comprise so that the hydraulic oil of a main tank may be directly supplied / discharged with respect to the valve unit VU, without providing the hydraulic oil tank 47. FIG.

  With this configuration, when a surge pressure is applied to one of the motor flow paths 51 when the spool position of the rotation control valve V is switched, the first connection flow path 52 connected to the motor flow path 51 and the relief are provided. The check valve 53 and the merging channel 54 flow, the relief valve 55 is opened, and the hydraulic fluid tank 47 is discharged from the tank channel 56. Thereby, the pressure of one motor channel 51 does not rise excessively.

  Further, when a negative pressure is applied to the other motor flow path 51 when the spool position of the rotation control valve V is switched, the suction connection is connected to the second connection flow path 58 connected to the motor flow path 51. The check valve 59 is opened, and the hydraulic oil in the hydraulic oil tank 47 flows from the tank flow path 56 to the branch flow path 57, and the other motor flow through the open check check valve 59 and the second connection flow path 58. It flows to the path 51 and reduces the effect of negative pressure.

  Thereby, even when the control device 48 alternately performs the forward drive control and the reverse drive control of the hydraulic motor M via the rotation control valve V during the operation, the rotation of the cooling fan 34 is suddenly stopped. Instead, it is possible to smoothly decelerate and stop while allowing rotation due to inertia, and then increase the rotational speed of the hydraulic motor M in the reverse direction.

[Operation / Effect of Embodiment]
The cooling fan 34 that supplies cooling air to the radiator 31 is rotated by the hydraulic motor M, and the rotation direction of the hydraulic motor M is switched by switching the supply / discharge direction of the hydraulic oil. Therefore, the rotation direction is switched using a clutch, a gear, or the like. The configuration is simplified compared to the one.

  In addition, since the dedicated hydraulic pump P for supplying the hydraulic oil to the hydraulic motor M and the dedicated rotation control valve V are disposed in the vicinity of the hydraulic motor M, the flow path piping for supplying and discharging the hydraulic oil is shortened. Accordingly, the drive system of the cooling fan 34 can be further reduced in size.

  A relief flow passage for releasing the pressure of one of the pair of motor flow paths 51 for supplying and discharging the hydraulic oil to and from the hydraulic motor M, and a hydraulic oil tank 47 when the other of the pair of motor flow paths 51 reaches a negative pressure state. A suction flow path for supplying the hydraulic fluid to the motor flow path 51 is formed. With this configuration, when a surge pressure is applied to one motor flow path 51 when the rotation direction of the hydraulic motor M is switched by operating the rotation control valve V, the hydraulic oil in the motor flow path 51 is supplied to the relief valve 55. The excess of the hydraulic oil can be suppressed from rising by being discharged to the hydraulic oil tank 47 via the. Further, when a negative pressure is applied to one of the motor flow paths 51, it is possible to increase the pressure by supplying hydraulic oil from the hydraulic oil tank 47 to the motor flow path 51 via the tank flow path 56. . As a result, even when the hydraulic motor that drives the cooling fan is switched between forward rotation and reverse rotation, no shock or excessive change in oil pressure is caused.

  Since the valve unit VU includes the rotation control valve V and includes the relief flow path and the suction flow path, it is not necessary to provide the relief valve 55, the relief check valve 53, and the suction check valve 59 outside. The road configuration is simplified.

  Since the pump bracket 38 is supported with respect to the machine frame 8 so that the position thereof can be adjusted, the counter shaft 22 and the input shaft of the hydraulic pump P can be easily aligned. The flexible joint 39 is also configured to absorb the core blur when there is a slight misalignment in the center alignment.

  INDUSTRIAL APPLICABILITY The present invention can be used for a work vehicle that switches a rotation direction of a cooling fan between forward and reverse by a hydraulic motor.

22 Counter shaft 22a Traveling transmission mechanism (second traveling transmission mechanism)
31 Radiator 33 Dustproof net 34 Cooling fan 40 Radiator frame 47 Hydraulic oil tank 51 Motor flow path 52 First connection flow path 53 Relief check valve 54 Merge flow path 55 Relief valve 56 Suction flow path (tank flow path)
58 Second connection flow path 57 Branch flow path 59 Check valve for suction E Engine F Airframe (traveling airframe)
M Hydraulic motor P Hydraulic pump V Rotation control valve

Claims (10)

A radiator that cools cooling water of the engine, a dust net disposed outside the fuselage from the radiator, a cooling fan that is disposed inside the fuselage and supplies cooling air to the radiator, and drives the cooling fan A hydraulic motor,
A hydraulic pump driven by the engine, and a rotation control valve for controlling hydraulic oil supplied from the hydraulic pump to the hydraulic motor;
The hydraulic motor is configured to rotate forward when hydraulic oil flows from one of the pair of motor flow paths to the other, and reverse when hydraulic oil flows in the opposite direction. Select the motor flow path and supply hydraulic oil.
A work vehicle including a communication channel between the pair of motor channels and the hydraulic oil tank.   2. The work vehicle according to claim 1, wherein the communication flow path is configured as a relief flow path including a relief valve that is opened due to an increase in pressure of the motor flow path and discharges hydraulic oil to the hydraulic oil tank.   A relief check valve that allows only a flow in a discharge direction of hydraulic oil from the first connection flow path, and a relief check valve that allows the relief flow path to connect to each of the pair of motor flow paths; The work vehicle according to claim 2, further comprising: a single merging passage for joining the hydraulic oil that has flowed through the relief check valve; and a relief valve connected to the merging passage.   The communication flow path is configured as a suction flow path including a check valve for suction that opens when the motor flow path becomes negative pressure and supplies hydraulic oil in the hydraulic oil tank to the motor flow path. The work vehicle according to claim 1.   The suction flow path is connected to each of a suction flow path communicating with the hydraulic oil tank, a branch flow path for branching and feeding the hydraulic oil sucked in the suction flow path, and a pair of the motor flow paths. A flow path of hydraulic fluid from the branch flow path to the second connection flow path at a position where the check valve for suction connects the branch flow path and the second connection flow path. The work vehicle according to claim 4, which is provided in an allowable state. The axis of the output shaft of the engine is set in a posture along the left-right direction of the fuselage, the cooling fan and the radiator are arranged outside the fuselage from the engine,
The output shaft is disposed on the opposite side of the radiator in the left-right direction of the airframe, and a counter shaft that is rotated by a driving force from the output shaft is disposed in a posture along the left-right direction of the airframe. The work vehicle according to claim 1, wherein a driving force from an end position is transmitted to the hydraulic pump.   The work vehicle according to claim 6, further comprising a traveling transmission mechanism that transmits a driving force of the counter shaft to a traveling transmission case of the airframe.   The work vehicle according to any one of claims 1 to 7, wherein the cooling fan and the hydraulic motor are disposed above a central position in the vertical direction of the engine.   The said radiator and the said hydraulic motor are supported by the radiator frame standingly arranged in the said body, and the said hydraulic pump is arrange | positioned in the position adjacent to the said radiator frame. Work vehicle.   The work vehicle according to any one of claims 1 to 5, wherein the hydraulic oil tank is disposed in the vicinity of a radiator frame that supports the radiator.

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