JP2001049700A - Hydraulic system for tractor mount type backhoe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shut off hydraulic pressure supply to a lift arm during the mounting of a backhoe and prevent interference with the lift arm by changing over and supplying the hydraulic pressure of a main hydraulic pump to the lift arm and the backhoe by a changeover spool. SOLUTION: In a backhoe mounted detachably on a tractor, hydraulic pressure is fed through an exclusive circuit 37A and a control valve 29 by an exclusive hydraulic pump to a swing cylinder 23, and fed through each control valve 30-34 via a directional control valve 39 and a control valve 40 by a main hydraulic pump 36 to other cylinders 24-27. A changeover spool is provided on the control valve 40 to change over and feed hydraulic pressure to a hydraulic device 10. Thereby in the case where a backhoe is mounted, hydraulic pressure feed is shut off to the hydraulic device 10, the backhoe is arranged close to a tractor, the front and rear weight balance of the tractor is improved, and entire length can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic system for a tractor-mounted backhoe.

[0002]

2. Description of the Related Art For example, in Japanese Unexamined Patent Application Publication No. 9-9713, a work vehicle (a so-called T.T.
LB) are disclosed. The TL / B includes a main circuit (main line) for supplying (supplying / discharging) hydraulic oil from a pump driven by an engine to each control valve in order to operate the front loader and the backhoe with hydraulic pressure. ing.

[0003]

In a tractor-mounted backhoe, when the backhoe is mounted on a tractor, it is not necessary to hydraulically drive a hydraulic device having a lift arm provided on the tractor. When mounted, the hydraulic device is driven by hydraulic pressure, and therefore, there is provided hydraulic switching means for switching the hydraulic pressure from the main hydraulic circuit to the control valve of the backhoe and the control valve of the hydraulic device, respectively. Conventional hydraulic switching means
It is provided in the return circuit from the backhoe to the tractor, and is a hydraulic system that can hydraulically drive a hydraulic device having a lift arm even when the backhoe is mounted, in which the hydraulic device is driven with the backhoe mounted And the interference between the lift arm and the components of the backhoe, the backhoe must be attached to the tractor so as to be far away from the tractor (separated back and forth to eliminate interference with the lift arm).

[0004] This is because the rear wheel load (particularly during running while the backhoe is raised and held up) increases with the increase in the size of the backhoe and the running stability is lacking, so that the backhoe is mounted near the tractor. Was contradictory to the current situation. Therefore, an object of the present invention is to shut off the supply of hydraulic oil to a hydraulic device when a backhoe is mounted so that the lift arm is not hydraulically driven, so that the backhoe can be mounted closer to the tractor. It is.

[0005]

SUMMARY OF THE INVENTION The present invention provides a tractor T having a hydraulic device 10 having a lift arm 10A.
In the case where the backhoe B is detachably attached,
The following technical measures have been taken to achieve the above objectives. That is, the hydraulic system of the tractor-mounted backhoe according to the present invention is characterized in that the tractor-mounted backhoe hydraulic system is provided with hydraulic switching means 60 for preventing the hydraulic device 10 from being hydraulically driven when the backhoe B is mounted on the tractor T. (Claim 1).

In the first aspect, the hydraulic pressure switching means 6
0 is provided so as to be switchable from behind the tractor T.
The control valve 28 can be switched to supply hydraulic pressure to one of the control valves 28 (claim 2). With this configuration, when the backhoe B is moved and mounted on the tractor T, the oil pressure is not supplied to the control valve 28 of the backhoe B unless the oil pressure to the hydraulic device 10 is shut off (to the hydraulic device 10). Therefore, when the backhoe B is mounted, the hydraulic device 10 cannot be hydraulically driven when the backhoe B is mounted, and it is possible to mount the backhoe B very close to the tractor T. .

Therefore, when the tractor T travels (moves) with the rotor L and the backhoe B raised and held in the TL, L and B, the front-rear weight balance is improved and the traveling stability can be ensured. Since the total length can be shortened, for example, not only can the vehicle be transported by a 10,000 pound trailer, but also the shift of the driver's seat 11 of the tractor T between the loader working posture (forward driving) and the backhoe working posture (rearward driving) is performed. It became possible while standing.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 4 showing the entire work vehicle 1 to which the hydraulic circuit according to the present invention is applied and FIG. 1 showing the entire configuration of the hydraulic circuit S, the work vehicle 1
It comprises a two-axle, four-wheel tractor T having left and right front wheels 2 and left and right rear wheels 3, a front loader L mounted at the front of the tractor T, and a backhoe B mounted at the rear of the tractor T. A so-called TLB working vehicle is illustrated.

The left and right front wheels 2 of the tractor T can be steered by a power steering 4, and a vehicle body 5 of the tractor T has a clutch housing 6 and a transmission case 7 connected in front and rear directions. 7 share a hydraulic oil tank, a hydraulic transmission 8 is provided in the clutch housing 6, and a gear transmission 9 is provided in the transmission case 7 as a transmission for the traveling system. A hydraulic device 1 having a lift arm on a rear upper surface of a vehicle body 5 for controlling lifting and lowering of a working machine such as a rotary tiller.
The hydraulic device 10 is provided with a driver's seat 11 capable of changing direction in the front-rear direction, and a reinforcement frame extending in the front-rear direction and fixed to the vehicle body 5 on the left and right sides of the vehicle body 5. Withstand 12

The front loader L includes left and right booms 14 whose bases are pivotably movable up and down on left and right masts 13, and buckets 15 provided at the distal ends of the booms 14. 17
Can be operated (driven). Backhoe B is mounting frame 1
8 is detachably provided at the rear of the tractor body 5,
8, a boom 20 and an arm 22 having a bucket 21 are provided so as to be freely bent. The swing bracket 19 is a left and right swing cylinder 23, the boom 20 is a boom cylinder 24, and the arm 22 is an arm. The cylinder 25 and the bucket 21 can be driven (operated) by a bucket cylinder 26 and include a pair of left and right stabilizers 27.

[0011] Stabilizer 27, each cylinder 23-26
Can be controlled by the valves 29 to 34 shown in FIG. 1 in the control box 28 when the driver's seat 11 is turned backward. In the hydraulic circuit S shown in FIG. 1, the pumps 35, 36, and 37 driven by the engine M suck the hydraulic oil stored in the hydraulic oil tank (substantially the vehicle body) T through a filter 38, and the pump 35 Through 37, liquid can be sent to each drive unit (cylinder and the like). The first pump 35 is for the power steering 4, and the second pump (main pump) 36 receives a part of the oil through the directional control valve 39 to the control valve 40 of the hydraulic device 10 and the remaining oil Are the control valve 41 and the horizontal control valve 4 of the front loader L.
2 can be sent.

The third pump 37 can supply liquid to each of the control valves 29 to 34 in the control box 28 of the backhoe B via a coupler 43A which can be connected to and separated from the directional control valve 43, and the main pump 36 is a directional control valve 39. Is supplied to the control valve 40 of the hydraulic device 10 via the hydraulic pump 10, and a portion of the oil from the control valve 40 is connected to the hydraulic take-out port 40 </ b> A and the coupler 4 that can be connected and separated.
The liquid can be sent to the valve of the control box 28 via the OB. That is, the hydraulic system (hydraulic circuit) according to the present invention includes the left and right swing cylinders 23 that swing the boom 20 of the backhoe B mounted on the tractor T in the left and right directions as shown in FIGS. 1, 3, and 4. A control valve 29 for controlling the swing cylinder 23
And an independent swing circuit 37A for supplying and discharging hydraulic oil from the dedicated third pump 37 to the control valve 29.

More specifically, as shown in FIG. 2, downstream of a control valve 29 for controlling the swing cylinder 23,
Boom cylinder 24, pair of stabilizer cylinders 2
7, control valves 30, 31, 32, and 3 for controlling each of the arm cylinder 25 and the bucket cylinder 26
3, 34 are connected in a parallel arrangement. Further, a front loader L is mounted on the tractor T, and the boom and bucket cylinders 16,
The control valve 41 is provided downstream of the control valve 29 for controlling the swing cylinder 23 by diverting hydraulic oil supplied and discharged by the main pump 36 to the control valves 41 and 42 by the direction control valve 39. They are joining.

Referring to FIGS. 1 and 3, the relationship between the power steering 4 and the hydraulic transmission 8 is illustrated. The power steering 4 switches the rotary valve 4B by rotating the handle 4A, and the power cylinder is controlled by the controller 4C. The left and right front wheels 2 can be steered by expanding and contracting 4D right and left R and L, and the relief valve 4
E, a check valve 4F and the like. The hydraulic transmission 8 includes a charge pump 8D that connects a variable displacement hydraulic pump 8A driven by the engine M and a fixed displacement hydraulic motor 8B by a closed circuit 8C, and is driven by the engine M. The charge pump 8
D sucks the hydraulic oil in the tank T through the filter 44 and makes it possible to replenish the leak in the closed circuit 8C through the filter 45.

Further, an oil cooler 46 is provided downstream of the charge circuit in the hydraulic transmission 8, and the return oil from the oil cooler 46 is transmitted to the gear transmission 9 via a first pipe 47 as shown in FIG. To the transmission case 7 having the hydraulic transmission 8 and the clutch housing 6 having the hydraulic transmission 8 via a second pipe 48 branched from the first pipe 47. I have. Referring to FIG. 5, the first pump 35 and the second pump 36 are mounted on the front wheel bearing stand 49 together with the oil cooler 46, and the third pump 37 is mounted on the side of the engine M.

The first to third pumps 35 to 37 filter the hydraulic oil (for lubrication and cooling) in the transmission case 7 into a double filter 38.
And the liquid can be sent to the power steering controller 4C and the loader port block 50 via the pipes 50A and 50B, and the operating oil pressure from the controller 4C is sent to the power cylinder 4D via the pipes 51A and 51B. The charge pump 8D in the hydraulic transmission 8 communicates with a charge port via a suction pipe 52. Return oil from the controller 4C communicates with the charge port via a pipe 54 to the suction side of the charge circuit. (See FIG. 3).

The oil cooler 46 is provided on the lower side of the charge circuit via a pipe 55.
The return oil of No. 6 is divided and returned to the clutch housing 6 and the transmission case 7 via the first and second pipes 47 and 48 for lubrication or cooling, respectively.
The return circuit (piping 54) of the power steering 4 is the suction circuit 52 of the charge pump in the hydraulic transmission 8.
(Charge port). In FIG. 3, a high pressure relief valve 56, a charge relief valve 57, and a relief valve 5 provided in a pilot line are shown.
The hydraulic transmission 8 includes a direction control valve 59, a double-acting cylinder 60 with a spring, and the like.

In FIG. 5, a front axle supporting the front wheel 2 so as to be steerable via a kingpin is supported by a front wheel bearing stand 49 or the like via a center pin. According to the hydraulic circuit S configured as described above, the return oil from the oil cooler 46 provided downstream of the charge circuit is diverted through the first pipe 47 and the second pipe 48, and is divided into the front transmission section (the hydraulic transmission). 8) and return to the transmission case 7 having the rear transmission (gear transmission 9) and lubricate each part.
Hydraulic oil in the vehicle body 5 which has been cooled to form the hydraulic oil tank T can be circulated as a whole to prevent a local temperature rise of the hydraulic oil and to prevent early deterioration of the hydraulic oil.

Since the return oil of the power steering 4 is connected to the suction side of the charge pump 8D via the pipe 54 and is joined to the transmission case 7 by the pipe 52, the return oil from the power steering 4 can be reduced. A, when the suction oil amount of the charge pump 8D is B, and when A> B, the excess supply oil amount is returned to the tank (the transmission case 7) by the pipe 52 so that the charge oil temperature can be lowered and the oil in the entire circuit can be reduced. Can be improved, and when B> A, the shortage of supply to the charge port is compensated for, and the loss horsepower of the charge pump 8D can be reduced.

That is, even if the flow rate of the power steering system fluctuates (for example, charging of the closed circuit 8C of the hydraulic transmission is stopped at the time of relief operation, or the amount of supplied oil changes due to a reduction in the volumetric efficiency of the pump 8A). It works to maintain balance and reduces the loss horsepower with the charge pump. Referring to FIG. 3 and FIGS. 6 to 8, details of the hydraulic device 10 having the directional control valve 43 and the hydraulic outlet port 40A, the reinforcing frame 12, and the like are shown. The direction control valve 43 for the control valve 29 for controlling the left and right swing cylinders 23 has a third swing-only (priority) control.
Hydraulic oil from the pump 37 is sent through a delivery pipe (swing circuit) 37A, and the direction control valve 43 is provided on the right front side of the casing of the hydraulic device 10 having the left and right lift arms 10A as shown in FIG. It is attached to.

As shown in FIG. 8, the hydraulic pressure switching block 43B of the direction control valve 43 is provided with a switching spool 43D for switching hydraulic pressure by an operating tool 43C and a relief valve 43E, and a pair of connection ports having couplers 43A, 43A. One of 43F and 43G is for an inlet port (import connection port), and the other is for a tank port (out port connection port). When the backhoe B is mounted on the tractor T and working, a swing circuit (delivery pipe) is used. ) 3
7A, the oil from the dedicated pump 37 is supplied to the direction control valve 4
3 and the oil from the directional control valve 43
A, swing valve 29 through connection ports 43F and 43G
Boom 20 swings in the left and right directions about the swing axis by swinging each of the swing cylinders 23, and the amount of oil supply to the swing cylinder 23 becomes constant. The same operability can be obtained in the simultaneous operation.

On the other hand, when the backhoe B is detached from the tractor T, the switching spool 4 is operated by the operating tool 43C.
By switching the 3D to have the unload function, a service port different from the main circuit can be provided via the coupler 43A and the connection ports 43F and 43G. That is, as shown in FIG. 8, by operating the operating tool 43C to switch the spool 43D so as to have the unload function, the relief valve 43E can set a system relief pressure different from that of the main circuit.
When the backhoe B is detached by configuring the service port by the F and 43G, it can be used for a wide range of uses as a hydraulic supply source (service port) for other hydraulic equipment. At this time, the relief valve 43E is, for example, a cartridge type or the like. It can be used for a wider range of applications by making it replaceable.

The return oil from the switching block (direction control valve) 43 is returned to the tank (tractor body) T via a pipe 43H. Referring to FIGS. 5 to 8, the switching valve means (directional control valve) 43 having a service port that can set a system relief pressure different from the main circuit,
It is mounted on the right side of a hydraulic device 10 mounted on the tractor body 5, but on the left side of the hydraulic device 10 is a hydraulic switching means 6
0 is attached. That is, an oil passage switching block (oil pressure switching means) 60 is provided on the hydraulic pressure delivery side (supply side) of the hydraulic device 10 and the backhoe B.

The switching means 60 connects the supply pipe 39A of the direction control valve 39 shown in FIG. 3 to the backhoe B side by the switching spool 60A at the upstream side of the control valve (position control valve) 10B in the hydraulic device 10. The apparatus 10 is provided with a switchable hydraulic pressure. That is, as shown in FIGS. 5 to 7, the switching block 60 is provided on the left side front portion of the hydraulic housing 10 </ b> C that constitutes the hydraulic device 10.
B is removably mounted. The block 60B is provided with a coupler 40B via a hydraulic outlet 40A to supply hydraulic pressure from the main pump 36 to the control valve 28 of the backhoe B. A switching spool 60A that can be switched between when the hydraulic pressure from the pump 36 is supplied to the valve 10B and the knob 60C that extends rearward on the left side surface of the hydraulic housing 10C is provided. The switching operation can be freely performed by an operation tool 60D having the following.

The switching spool 60A is rotatably supported by a block 60B around an axis in the left-right direction, and the tip (front end) of a rod-like operating tool 60D is pinned to an arm 60E provided at the end of the spool 60A. The hydraulic pressure from the pipe 39A is applied to the control valve 1
The position A1 of the knob 60C indicated by the solid line in FIG. 7 is when the backhoe B is used (the liquid is sent to the control valve 28 side). The position A2 shows the case where the backhoe B is detached and the hydraulic device 10 uses a so-called 3P in which a working machine different from the backhoe can be moved up and down via a three-point link or the like.

That is, in the related art, the hydraulic pressure switching means 60 is provided in the return oil passage from the backhoe to the tractor, so that the hydraulic circuit can operate the hydraulic device 10 even when the backhoe is mounted.
In this conventional example, when the backhoe B is mounted, the lift arm 10A can move up and down.
The backhoe B must be mounted away from the tractor body 5 (at an interval of front and rear) so as not to interfere with the vertical movement of 0A, and this causes the weight balance of the TLB to deteriorate and stability during running. Or the length of the TLB was increased, making it impossible to transport it on a 10,000 pound trailer, for example.

On the other hand, according to the hydraulic pressure switching means 60 described above, when the backhoe B is mounted, the hydraulic device 1
Thus, the hydraulic circuit does not move 0, so that the backhoe B can be mounted close to the tractor body 5 and the disadvantage of the above-described conventional switching means is eliminated. That is, the hydraulic device 1 having the lift arm 10A
The backhoe B is detachably mounted on the tractor T provided with a zero. The hydraulic switch 10 is provided so as not to hydraulically drive the hydraulic device 10 when the backhoe B is mounted on the tractor T. The hydraulic pressure switching means 60 is provided so as to be switchable from behind the tractor T, and can be switched to supply hydraulic pressure to one of the control valve 10B of the hydraulic device 10 and the control valve 28 of the backhoe B. It is.

Although the embodiment of the present invention is as described above, the hydraulic switching means 43 and 60 can be freely designed, for example, can be mounted in opposite directions, and the rated flow rate of the first pump 35 is 22.5 l. / Min, the rated flow rate of the second pump (main pump) 36 is 47.9 l / min, and the rated flow rate of the third pump (pump dedicated to swing (priority)) 37 is 2
Although it is 7.7 l / min, it is also possible to set a flow rate other than that. Note that the hydraulic device 10 may be one that lifts and lowers the lift arms 10A individually or simultaneously with a hydraulic cylinder.

[0029]

As described above in detail, according to the present invention, the backhoe cannot be mounted unless the hydraulic pressure to the hydraulic device is shut off, which makes it possible to mount the backhoe close to the tractor. The weight balance can be properly adjusted, and the overall length can be shortened.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a hydraulic circuit according to the present invention.

FIG. 2 is a circuit diagram of a backhoe and a loader in a hydraulic path according to the present invention.

FIG. 3 is a circuit diagram of a hydraulic device and a power steering in a hydraulic path according to the present invention.

FIG. 4 is an overall side view showing a TLB as a working machine to which the present invention is applied.

FIG. 5 is a plan view showing an outline of a hydraulic pipe.

FIG. 6 is a rear view of the TLB.

FIG. 7 is a side view showing a hydraulic pressure switching means between the backhoe and the hydraulic device.

FIG. 8 is a plan view showing switching means for switching between the hydraulic pressure of the backhoe and the hydraulic pressure for the service port.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 T ・ L ・ BT T Tractor B Backhoe L Front loader 10 Hydraulic device 60 Hydraulic pressure switching means

Claims (2)

[Claims] 1. A tractor (T) having a hydraulic device 10 having a lift arm (10A) with a backhoe (B) detachably attached thereto, wherein the backhoe (B) is attached to the tractor (T). A hydraulic system for a tractor-mounted backhoe, comprising a hydraulic switching means (60) for preventing the hydraulic device (10) from being hydraulically driven. 2. The tractor (T) according to claim 1, wherein the hydraulic switching means (60) is a tractor (T).
And a control valve (10B) and a backhoe (B) in the hydraulic device (10).
The hydraulic system for a tractor-mounted backhoe according to claim 1, characterized in that the hydraulic system is switchable to supply hydraulic pressure to one of the control valves (28).