JP2009056983A - Working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a working fluid tank for supplying a working fluid to a hydrostatic continuously-variable transmission for traveling and hydraulic actuators of a working machine elevating device in a working vehicle such as a crawler tractor provided with the hydrostatic continuously-variable transmission for traveling (HST for traveling) of a two-pump and two-motor system. <P>SOLUTION: This working vehicle is provided with the exclusive working fluid tank T supplying the working fluid to the hydrostatic continuously-variable transmission 33 for traveling. Lubricating oil in a transmission case 41 is supplied to a hydraulic clutch 43 for connecting and disconnecting power to a working machine PTO shaft 42 linked with a PTO transmission 40 and the hydraulic actuators 17, 17 and 24 of the working machine elevating device 8 via a hydraulic pump 44. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a work vehicle such as a crawler tractor.

  2. Description of the Related Art Conventionally, a work vehicle such as a crawler tractor equipped with a two-pump two-motor-type traveling hydrostatic continuously variable transmission (traveling HST) includes a work machine lifting device that lifts and lowers a work machine connected to the rear part of the machine body. The working machine lifting / lowering device is provided with hydraulic actuators such as a pair of left and right working machine lifting / lowering cylinders and a working machine tilting cylinder.

In addition, a fuel tank is provided on the left and right sides of the cabin that covers the control section of the crawler tractor, while a hydraulic oil tank is provided on the other side. A charge pump is provided from the hydraulic oil tank. The hydraulic oil is supplied to the above-described hydrostatic continuously variable transmission for traveling via the gear pump, and the hydraulic oil sucked up from the same hydraulic oil tank via the gear pump is supplied to the hydraulic actuator of the work equipment lifting device. (For example, refer to Patent Document 1).
JP 2001-97062 A (page 2-3, FIG. 6)

  However, the hydraulic oil tank of Patent Document 1 is inevitably large in size (large capacity) to supply hydraulic oil to the hydraulic actuators of the hydrostatic continuously variable transmission for traveling and the lifting mechanism of the work implement. The hydraulic oil is sucked from the tank and supplied to the hydraulic actuator of the work implement lifting device, while the transmission is applied to the hydraulic clutch that turns on and off the power of the PTO transmission (work machine PTO shaft) that shifts the external take-out power built in the transmission case. Since the lubricating oil in the case is supplied as the hydraulic oil, a dedicated gear pump corresponding to each hydraulic oil tank and transmission case has to be provided, resulting in high costs. Note that when a tandem pump is used as the gear pump, it is necessary to prevent oil from entering by inserting an oil seal between the housings of the pumps constituting the tandem pump. There was room for improvement.

The present invention has been made to solve the above-described problems, and is connected to a fuselage, a hydrostatic continuously variable transmission for traveling, a transmission case having a PTO transmission for shifting external extraction power, and a fuselage. In a work vehicle equipped with a work implement lifting device for raising and lowering a work implement, a working oil tank is provided for supplying working oil to the hydrostatic continuously variable transmission for traveling, and lubricating oil in the transmission case is used for PTO transmission. A first feature is that the apparatus and the work implement elevating apparatus are supplied via a hydraulic pump.
The hydraulic oil supplied from the hydraulic pump is preferentially supplied to the PTO transmission device via the priority diversion valve, and the surplus flow is supplied to the work machine lifting device. It is said.

According to the first aspect of the present invention, the hydraulic oil tank for supplying the hydraulic oil to the hydrostatic continuously variable transmission for traveling is provided, and the lubricating oil in the transmission case is supplied to the PTO transmission and the working machine lifting device by the hydraulic pump. The hydraulic oil tank for supplying hydraulic oil to the traveling hydrostatic continuously variable transmission can be reduced in size, and the lubricating oil in the transmission case can be supplied in tandem. Since a single hydraulic pump can be used to supply the PTO transmission and work implement lifting device without adopting a pump, a dedicated hydraulic oil tank corresponding to the PTO transmission and work implement lifting device is not required, thereby reducing costs. I can plan.
According to the second aspect of the present invention, the hydraulic fluid supplied from the hydraulic pump is preferentially supplied to the PTO transmission via the priority diverter valve, and the surplus flow is supplied to the work implement lifting device. With this configuration, while using the transmission case as one hydraulic oil tank, it is possible to supply hydraulic oil at an appropriate constant flow rate to the PTO transmission and to efficiently use the lubricating oil in the transmission case. Cost can be reduced.

  Next, embodiments of the present invention will be described with reference to the drawings. 1 to 3 are a side view, a plan view, and a rear view of a crawler tractor 1 that is a work vehicle. The crawler tractor 1 includes a hood 4 that houses an engine 3 on a body frame 2, and a cabin 5. In the cabin 5, a steering section in which various operation levers and switches such as a seat (not shown), a steering handle H (see FIG. 6), which is a travel operation tool, and a main transmission lever 6 are arranged. 7 is provided.

  A three-point link type work machine lifting / lowering device 8 for connecting (attaching) work machines for performing various farm work is always installed in the rear lower part of the cabin 5 (the rear part of the machine body). Reference numerals 9L and 9R are a pair of left and right crawler type traveling devices, and the body frame 2 is supported on the crawler type traveling devices 9L and 9R.

  The crawler type traveling devices 9L and 9R are provided with a driving sprocket 11 and an idler 12 at the front and rear ends of the left and right traveling frames 10L and 10R integrally formed at the lower part of the body frame 2, and between the driving sprocket 11 and the idler 12. In addition, two sets of equalizer arms 14 including a pair of front and rear rollers 13 are supported on the lower portions of the traveling frames 10L and 10R so as to be swingable up and down.

  Further, an upper roller 15 is pivotally supported on the upper part of the front and rear intermediate positions of the left and right traveling frames 10L and 10R. A pair of front and rear rollers 13 provided on the drive sprocket 11, the idler 12 and the two sets of equalizer arms 14 are supported. The crawler type traveling devices 9L and 9R are configured by the crawler 16 wound around the upper roller 15.

  Further, as shown in the rear view of the crawler tractor 1 shown in FIG. 3 and the hydraulic circuit diagram of the crawler tractor 1 shown in FIG. The upper end of the piston rod 17b is connected to the lift arms 20 and 20, while the lower end of the piston rod 17b is pivotally supported by a pair of left and right stays 19 and 19 fixed to the rear wall 18 of the machine body.

  In other words, the lift arm bracket 21 installed horizontally on the upper portions of the stays 19 and 19 is provided with a horizontal boss 21a, and a pair of left and right lift arms 20 and 20 are connected to each other via a support shaft 22 inserted into the horizontal boss 21a. The piston rod 17b of the lift cylinder 17 is connected to a substantially intermediate portion of the lift arms 20 and 20 while being integrally connected so as to be swingable up and down.

  A pair of left and right lower links 22 and 22 are pivotally supported at the lower part of the pair of left and right stays 19 and 19, respectively, and a substantially intermediate portion of both lower links 22 and 22 and the tips of the lift arms 20 and 20 are connected to a lift rod. 23 and 23 are connected. Note that a lift rod cylinder (double-acting hydraulic cylinder) 24 (see FIG. 4) is interposed in either the left or right lift rod 23, and by operating the lift rod cylinder 24 to expand and contract, Rolling control that keeps the left and right tilt constant regardless of the tilt of the aircraft can be executed.

  Further, a support portion 21b that pivotally supports a single top link (not shown) is provided at the center of the lift arm bracket 21, and is constituted by this single top link and a pair of left and right lower links 22,22. A three-point link, a pair of left and right lift arms 20, 20 that suspends the three-point link via lift rods 23, 23, and lift cylinders 17, 17 that forcibly swing the lift arms 20, 20 up and down Thus, the working machine lifting / lowering device 8 capable of lifting and lowering is configured.

  Next, the hydraulic circuit of the crawler tractor 1 will be described with reference to FIG. The crawler tractor 1 supplies hydraulic oil to the traveling hydraulic motors 31L (left side) and 31R (right side) for driving the pair of left and right crawler traveling devices 9L and 9R and the traveling hydraulic motors 31L and 31R. A hydrostatic continuously variable transmission for travel (hereinafter referred to as travel HST) composed of closed circuits in which main ports of travel hydraulic pumps 32L (left side) and 32R (right side) are connected by hydraulic pipes Pa, Pb, Pc, and Pd, respectively. 33).

  The traveling hydraulic motors 31L and 31R rotate in proportion to the amount of hydraulic oil sent from the traveling hydraulic pumps 32L and 32R, and then are decelerated via the speed reducer units 34L and 34R. The crawler tractor 1 travels by rotating the drive sprocket 11 of the pair of left and right crawler type traveling devices 9L and 9R by the driving force.

  More specifically, the traveling hydraulic pumps 32L and 32R are variable displacement pumps that are driven by the power of the engine 3, and by changing the swash plate angle, the discharge amount of hydraulic oil can be changed steplessly and the discharge direction. Can also be changed at the same time, so that forward / reverse and stepless shifting (main shift) can be performed simultaneously, and by changing the amount of hydraulic oil supplied to the left and right traveling hydraulic motors 31L, 31R, the traveling hydraulic motor 31L, Smooth rotation of the aircraft is possible while giving a left-right difference in the rotational speed of 31R.

  Further, the traveling hydraulic motors 31L and 31R include a pair of tilting pistons 34 which are high and low speed shifting means for shifting the traveling hydraulic motors 31L and 31R in two steps, high speed and low speed connected to the tilting pistons 34. A switching valve 35 and a hydraulic parking brake 36 are integrally provided. The hydraulic parking brake 36 is operated by pushing a parking brake switch provided in the vicinity of a front panel (not shown) of the control unit 7. It operates via the brake switching valve 37.

  The charge pump 38 provided integrally with the traveling hydraulic pumps 32L, 32R sucks the hydraulic oil in the hydraulic oil tank T dedicated to the traveling HST 33, while being supplied via the charge pump 38. Is supplemented to the closed circuit of the traveling HST 33, and the swash plate control servo mechanisms S1, S2 change the discharge amount of the traveling hydraulic pumps 32L, 32R based on the operation of the steering handle and the main transmission lever 6. The pilot pressure oil is used as a pilot pressure oil, and further switches the sub-shift switch valve 39 to operate the high / low-speed switch valve 35 based on the operation of turning on or off the sub-shift switch (not shown), and the hydraulic parking brake 36. It is also used as hydraulic fluid.

  Further, as shown in FIG. 5, a transmission case 41 having a PTO transmission 40 for shifting the power for the work implement (external take-out power) is disposed below the seat provided in the control unit 7. The traveling hydraulic pumps 32L and 32R described above are integrally assembled on the upper portion of the transmission case 41, and the front portion of the transmission case 41 uses the lubricating oil in the transmission case 41 so that the working machine PTO shaft ( The hydraulic clutch 43 for turning on and off the power to the work machine power take-off shaft 42), the lift cylinders 17 and 17 which are the hydraulic actuators of the work machine lifting and lowering device 8, and the work hydraulic pump 44 to be supplied to the lift rod cylinder 24 are assembled. Yes.

  The power of the engine 3 input into the transmission case 41 via the flywheel 45 and the universal joint 46 of the engine 3 is a hydraulic clutch 43 that turns on and off the power to the work machine PTO shaft 42 built in the transmission case 41. , The drive shaft 47 and the PTO gear transmission 40a are transmitted to the work machine PTO shaft 42, and the drive shaft 48 of the traveling hydraulic pumps 32L and 32R described above and the drive of the work hydraulic pump 44 including the gear pump are driven. It is transmitted to the shaft 49.

  More specifically, the oil in the transmission case 41 is given priority to the hydraulic clutch 43 that turns on and off the power to the work machine PTO shaft 42 described above via a priority diversion valve 50 provided downstream of the work hydraulic pump 44. And the surplus flow can be supplied to the lift cylinders 17 and 17 and the lift rod cylinder 24 which are hydraulic actuators of the work implement lifting device 8.

  That is, the working hydraulic pump 44 supplies the hydraulic oil sucked from the transmission case 41 via the hydraulic pipe Pe to the priority diversion valve 50, and the hydraulic oil preferentially diverted by the priority diversion valve 50 is supplied to the hydraulic pipe. It is supplied to the PTO switching valve 43b that expands and contracts the piston 43a of the hydraulic clutch 43 via Pf. Further, excess oil in the PTO switching valve 43b is collected in the transmission case 41 while the hydraulic clutch 43 is wetted. On the other hand, the surplus flow of the priority diversion valve 50 is supplied to the hydraulic actuators 17, 17, 24 of the work implement lifting / lowering device 8 through a hydraulic pipe Pg connected to the center bypass oil passage 52 of the external hydraulic take-out device 51 described later, The return oil is collected in the transmission case 41 via the hydraulic pipe Ph.

  By the way, the crawler tractor 1 is assumed to be connected to an external hydraulic pressure take-out device (auxiliary device) assuming that a work machine such as a dozer is connected to the front part of the machine body or a work machine that requires a hydraulic actuator is connected to the rear part of the machine body. Control valve unit) 51 is provided. The working hydraulic pump 44 and the hydraulic device 53 of the work implement lifting device 8 are connected via the center bypass oil passage 52 of the multiple directional control valves 51a, 51b, 51c constituting the external hydraulic pressure take-out device 51. The hydraulic device 53 controls the operation of the lift cylinders 17 and 17 and the lift rod cylinder 24, and includes a work implement lowering speed adjustment valve 54 that adjusts the reduction operation speed of the lift cylinders 17 and 17. .

  The hydraulic device 53 includes a branch valve 53a for branching hydraulic oil supplied from the work machine hydraulic pump 44, a lift arm control valve 53b connected to one branch oil path, and a second branch oil path. A lift rod control valve 53c to be connected is inserted and configured as one assembly.

  As described above, in the present invention, the hydraulic oil tank T that supplies hydraulic oil to the traveling HST 33 of the crawler tractor 1 is used as a dedicated tank for the traveling HST 33 and also shifts the power for the work equipment. The hydraulic oil in the transmission case 41 having the interior 40 is supplied to the hydraulic clutch 43 for turning on and off the power to the work machine PTO shaft 42 and to the hydraulic actuators 17, 17, and 24 of the work machine lifting / lowering device 8. (Hydraulic pump for machine) 44 is used to reduce the size of the hydraulic oil tank T that supplies hydraulic oil to the traveling HST 33, and the lubricating oil in the transmission case 41 can be reduced. Without using a tandem pump, a single hydraulic pump 44 provides the PTO transmission 40 and work implement lifting device 8 to each other. Be so dedicated hydraulic oil tank that corresponds to the working machine lifting device 8 and the PTO speed change unit 40 can be reduced in cost becomes unnecessary.

  Then, the lubricating oil as the working oil supplied from the working hydraulic pump 44 is preferentially supplied to the hydraulic clutch 43 of the PTO transmission via the priority diverter valve 50, and the surplus flow is supplied to the work implement lifting device 8. By being configured to be supplied to the hydraulic actuators 17, 17, and 24, while using the transmission case 41 as one hydraulic oil tank, the hydraulic clutch 43 can be supplied with an appropriate constant flow rate of hydraulic oil, Since the lubricating oil in the transmission case 41 can be used efficiently, the cost can be reduced.

  Further, as shown in FIG. 6, the traveling HST 33 includes a traveling hydraulic motor 31L, in accordance with a turning operation of pump levers (swash plate operation levers) 55L, 55R provided in the left and right traveling hydraulic pumps 32L, 32R. The output rotation of 31R can be changed. That is, the steering handle H and the main speed change lever 6 are interlocked and connected to the link mechanism 56 via the left and right operation wires 57L and 57R, thereby the steering operation of the crawler tractor 1 by the steering handle H and the main speed change. The speed change operation of the crawler tractor 1 by the lever 6 can be freely performed.

  More specifically, the left and right operation wires 57L and 57R are provided with electric actuators 58L and 58R that operate a small amount of the pump levers 55L and 55R in an auxiliary manner. The electric actuators 58L and 58R are configured such that the pump levers 55L and 55R can be operated in a small amount by displacing the outer casing 57b among the inner cable 57a and the outer casing 57b constituting the left and right operation wires 57L and 57R. ing.

  The minute operation (control) of the pump levers 55L and 55R described above is performed by the traveling control microcomputer 60 provided in the crawler tractor 1 as shown in the block diagram of FIG. (Sub-shift) Valve selector switch 61, left crawler rotation pickup sensor 62L, right crawler rotation pickup sensor 62R, engine rotation pickup sensor 63, left pump lever rotation position detection sensor 64L, right pump lever rotation position detection sensor 64R, main Shift lever operation position detection sensor 65, steering wheel steering angle detection sensor 66, left operation wire outer casing position detection sensor 67L, right operation wire outer casing position detection sensor 67R, left electric actuator operation amount detection While connecting sensors 68L, and a right side electric actuator operation amount detecting sensor 68R, the output side, the left and right electric actuators 58L, is connected to 58R.

  When a rotary tiller (not shown) is connected to the rear part of the body of the crawler tractor 1 to perform tilling work on the field, if the rotary resistance of the rotary increases and the rotational speed of the engine 3 decreases, the engine rotation pickup sensor 63 In this case, a control signal is input to the travel control microcomputer 60, and in this case, the travel hydraulic pumps 32L and 32R of the travel HST 33 are reduced in the discharge amount, that is, to the travel hydraulic pumps 32L and 32R. A control signal is sent from the travel control microcomputer 60 to the left and right electric actuators 58L, 58R so that the pump levers 55L, 55R provided are rotated in a direction to reduce the output rotation of the travel hydraulic motors 31L, 31R. Output, then when the speed of the engine 3 recovers to a predetermined value, Actuators 58L, is performed cruise control to stop the operation of the 58R.

  According to the traveling control described above, even if an engine drop occurs during the traveling of the crawler tractor 1, the rotation of the work implement PTO shaft (work implement power take-off shaft) 42 can be automatically maintained constant. When there is a margin in the load of the engine 3 during traveling, the direction of increasing the discharge amount of the left and right traveling hydraulic pumps 32L, 32R of the traveling HST 33, that is, pump levers 55L, 55R provided in the traveling hydraulic pumps 32L, 32R. However, by controlling to automatically rotate in the direction of increasing the output rotation of the traveling hydraulic motors 31L and 31R, the traveling speed of the airframe can be automatically increased so that efficient work traveling can be performed. become.

The side view of a crawler tractor. The top view of a crawler tractor. The back view of a crawler tractor. The hydraulic circuit diagram of a crawler tractor. The principal part sectional side view which shows the structure around a hydraulic clutch and a PTO transmission. The block diagram which shows the traveling operation mechanism of a crawler tractor. The block diagram of the microcomputer for driving | running | working control.

Explanation of symbols

8 Working Machine Elevating Mechanism 33 Hydrostatic continuously variable transmission for traveling (HST for traveling)
40 PTO transmission 41 Transmission case 44 Hydraulic pump (hydraulic pump for work equipment)
50 Priority shunt valve T Hydraulic oil tank

Claims (2)

  A hydrostatic continuously variable transmission (33) for traveling, a transmission case (41) equipped with a PTO transmission (40) for shifting external take-out power, and a working machine lifting device ( 8) provided with a hydraulic oil tank (T) for supplying hydraulic oil to the hydrostatic continuously variable transmission (33) for traveling, and lubricating oil in the transmission case (41), A work vehicle characterized by being supplied to a PTO transmission (40) and a work implement lifting device (8) via a hydraulic pump (44).   The hydraulic fluid supplied from the hydraulic pump (44) is preferentially supplied to the PTO transmission (40) via the priority diverter valve (50), and the surplus flow is supplied to the work implement lifting device (8). The work vehicle according to claim 1 configured as described above.

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