JP3652929B2 - Tractor-mounted backhoe hydraulic system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic system for a tractor-mounted backhoe.
[0002]
[Prior art]
For example, Japanese Patent Application Laid-Open No. 9-9713 discloses a work vehicle (so-called T · L · B) in which a front loader is attached to the front portion of a tractor and a backhoe is attached to the rear portion of the tractor.
This T / L / B is equipped with a main circuit (main line) that sends (supply / discharge) hydraulic oil from a pump driven by the engine to each control valve in order to operate the front loader and backhoe hydraulically. ing.
[0003]
[Problems to be solved by the invention]
In conventional tractor-mounted backhoes, hydraulic pressure is supplied from a single pump (main pump) to a control valve that controls the backhoe.
On the other hand, since the backhoe performs complex operations such as turning and excavating operations, when operating the sections of the control valve at the same time, if the operation speed is slow, the work efficiency decreases, so the pump has a large capacity. Something is needed.
However, the swing operation for swinging the backhoe boom in the left-right direction is operated independently without being combined with the excavation operation, and the swing operation has a smaller load than the excavation operation.
[0004]
Therefore, when a large-capacity pump is used in consideration of combined work (simultaneous operation), the flow rate is excessive in the single swing operation, and therefore, the swing speed at which the driver excessively flows when operating by holding the swing lever. In addition, the operability was reduced and the operability was reduced, and the driver's feeling of fatigue was great because the operation nerves were too sensitive.
In addition, since the load of the swing section is smaller than that of the other sections, hydraulic oil flows into the swing section when the swing and other sections are operated at the same time, causing the flow rate of the other sections to be insufficient and the operability to slow down (decrease) It was.
[0005]
Accordingly, an object of the present invention is to provide a hydraulic system that solves the above-described problems by providing a swing dedicated hydraulic circuit independent of the main circuit of the large-capacity pump.
[0006]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention takes the following technical means.
That is, the hydraulic system for a tractor-mounted backhoe according to the present invention includes a left and right swing cylinder 23 that swings the boom 20 of the backhoe B mounted on the tractor T in the left-right direction, and a control valve 29 that controls the swing cylinder 23. And an independent swing circuit 37A for supplying and discharging hydraulic oil from a dedicated pump 37 to and from the control valve 29 (Claim 1).
[0007]
Further, the present invention is described above Te claim 1 odor, blanking Mushirinda 24, the stabilizer cylinders 27 pairs, parallel arranged a control valve 30,31,32,33,34 controlling each of the arm cylinder 25 and bucket cylinder 26 (Claim 2). Further, in claim 1 or 2, the tractor T is equipped with a front loader B, and control valves 41 and 42 for controlling the front loader L are provided. It is recommended that the hydraulic oil supplied to and discharged from the control valves 41 and 42 is diverted and joined to the downstream side of the control valve 29 that controls the swing cylinder 23 (Claim 3).
[0008]
In other words, by providing the swing-specific pump 37 to provide the swing single circuit 37A, it is possible to secure the optimum amount of oil supplied to the left and right swing cylinders 23.
That is, since the amount of hydraulic oil supplied to the left and right swing cylinders 23 is constant, the same operability can be obtained in both the single operation and the simultaneous operation, the driver's feeling of fatigue is reduced, and the light operation can be performed. I promise.
Further, since the main circuit such as the boom 20 becomes a main-only supply circuit (parallel circuit) in the simultaneous operation, stable operability can be obtained, and by separating the swing circuit and the main circuit, a system different from the main circuit is obtained. It became possible to set the relief pressure.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 4 which shows the whole working vehicle 1 to which the hydraulic circuit according to the present invention is applied and in FIG. 1 which shows the entire configuration of the hydraulic circuit S, the working vehicle 1 includes a left and right front wheel 2 and a left and right rear wheel. An example of a so-called TLB work vehicle composed of a two-shaft, four-wheel tractor T having three, a front loader L attached to the front portion of the tractor T, and a backhoe B attached to the rear portion of the tractor T Yes.
[0010]
The left and right front wheels 2 of the tractor T can be steered by a power steering 4, and the vehicle body 5 of the tractor T is configured by connecting a clutch housing 6 and a transmission case 7 in the front and rear directions. The hydraulic oil tank 8 is shared by the clutch housing 6 and the gear mission 9 is incorporated in the transmission case 7 as a transmission system.
A hydraulic device 10 having a lift arm for controlling the raising and lowering of a working machine such as a rotary tiller is installed on the rear upper surface of the vehicle body 5, and a driver's seat capable of changing its direction in the front-rear direction is mounted on the hydraulic device 10. 11, and further, on the left and right sides of the vehicle body 5, there are provided reinforcement frame resistances 12 extending in the front-rear direction and fixed to the vehicle body 5.
[0011]
The front loader L includes left and right booms 14 whose bases are pivotally supported on the left and right masts 13 and a bucket 15 provided at the tip of the boom 14. The front loader L is operated by a pair of left and right boom cylinders 16 and 17. (Driving) is possible. The backhoe B includes a mounting frame 18 detachably attached to the rear part of the tractor vehicle body 5, and a swing bracket 19 provided in the frame 18 is provided with a boom 20 and an arm 22 having a bucket 21 so as to be bent. The swing bracket 19 can be driven (operated) by the left and right swing cylinders 23, the boom 20 can be driven by the boom cylinder 24, the arm 22 can be driven by the arm cylinder 25, and the bucket 21 can be driven by the bucket cylinder 26, and can be configured to include a pair of left and right stabilizers 27. ing.
[0012]
The stabilizer 27 and the cylinders 23 to 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, 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 the filter 38 and pump 35. The liquid can be fed to each drive unit (cylinder or the like) by .about.37.
The first pump 35 is for the power steering 4, and the second pump (main pump) 36 passes a directional control valve 39, and part of the oil is supplied to the control valve 40 of the hydraulic device 10 and the remaining oil. Can be fed to the control valve 41 and the horizontal control valve 42 of the front loader L.
[0013]
The third pump 37 can send liquids to the control valves 29 to 34 in the control box 28 of the backhoe B via a directional control valve 43 and a coupler 43A that can be joined and separated, and the main pump 36 is supplied via a directional control valve 39. Liquid is fed to the control valve 40 of the hydraulic device 10, and a part of the oil from this can be fed to the valve of the control box 28 through a coupler 40B that can be joined and separated from the hydraulic pressure take-out port 40A.
That is, the hydraulic system (hydraulic circuit) according to the present invention includes left and right swing cylinders 23 that swing the boom 20 of the backhoe B mounted on the tractor T in the left-right direction as shown in FIGS. 1, 3, and 4. And 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.
[0014]
More specifically, connecting blanking Mushirinda 24, a pair of stabilizer cylinder 27, the control valve 30,31,32,33,34 controlling each of the arm cylinder 25 and bucket cylinder 26 in parallel arrangement, Figure 1 As shown in FIG. 3, the oil of the main pump 36 is fed through the direction control valve 39 and the coupler 40B .
Furthermore, a front loader L is mounted on the tractor T, and control valves 41 and 42 for controlling the cylinders 16 and 17 of the boom and bucket of the front loader L are provided. The control valves 41 and 42 are supplied and discharged by the main pump 36. The hydraulic oil to be diverted is diverted by the direction control valve 39 and is merged downstream of the control valve 29 for controlling the swing cylinder 23.
[0015]
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 moves the power cylinder 4D left and right by the controller 4C. The left and right front wheels 2 can be steered by expanding and contracting to R and L, and includes a relief valve 4E, a check valve 4F, and the like.
The hydraulic transmission 8 includes a variable displacement hydraulic pump 8A driven by the engine M and a fixed displacement hydraulic motor 8B connected by a closed circuit 8C and a charge pump 8D driven by the engine M. The charge pump 8D can suck in the hydraulic oil in the tank T through the filter 44 and supply the leak from the closed circuit 8C through the filter 45.
[0016]
Further, an oil cooler 46 is provided on the downstream side of the charge circuit in the hydraulic transmission 8. As shown in FIG. 5, the return gear from the oil cooler 46 is included in the gear mission 9 via the first pipe 47. In addition to returning to the transmission case 7, the flow is divided and returned to the clutch housing 6 having the hydraulic transmission 8 through the second pipe 48 branched from the first pipe 47.
Referring to FIG. 5, the first pump 35 and the second pump 36 are mounted on the front wheel bearing base 49 together with the oil cooler 46, and the third pump 37 is mounted on the side portion of the engine M.
[0017]
The first to third pumps 35 to 37 suck the hydraulic oil (for lubrication and cooling) in the mission case 7 through the pipe 49 through the double filter 38 and the power steering controller 4C and the loader port block 50 through the pipes 50A and 50B. The operation hydraulic pressure from the controller 4C can be supplied to the power cylinder 4D via the pipes 51A and 51B, and the charge pump 8D in the hydraulic transmission 8 communicates with the charge port via the suction pipe 52. The return oil from the controller 4C communicates with the charge port via the pipe 54 to the suction side of the charge circuit (see FIG. 3).
[0018]
The oil cooler 46 is provided on the lower side of the charge circuit via a pipe 55, and the return oil of the oil cooler 46 is lubricated or cooled to the clutch housing 6 and the transmission case 7 via the first and second pipes 47 and 48. Each of them is divided and recirculated for use, and the return circuit (pipe 54) of the power steering 4 is connected to the suction circuit 52 (charge port) of the charge pump in the hydraulic transmission 8.
In FIG. 3, the hydraulic transmission 8 includes a high-pressure relief valve 56, a charge relief valve 57, a relief valve 58 provided in a pilot pipeline, a direction control valve 59, a spring-loaded double acting cylinder 60, and the like.
[0019]
In FIG. 5, the front axle that supports the front wheel 2 so as to be steerable via the king pin is supported by the front wheel bearing stand 49 and the like via the 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 the front mission section (hydraulic mission) 8) The clutch housing 6 having an internal structure and the transmission case 7 having a rear transmission (gear transmission 9) are recirculated (divided) to lubricate and cool the respective parts to form a hydraulic oil tank T. The hydraulic oil 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.
[0020]
Further, 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 joined to the transmission case 7 by the pipe 52, the amount of return oil from the power steering 4 is A, the charge When the suction oil amount of the pump 8D is B, when A> B, the oversupply oil amount is returned to the tank (mission case 7) by the pipe 52, the charge oil temperature can be lowered, and the oil circulation performance in the entire circuit On the other hand, when B> A, the shortage of supply to the charge port is compensated, so that the loss horsepower of the charge pump 8D can be reduced.
[0021]
That is, the flow rate balance is maintained even when the flow rate of the power steering system fluctuates (for example, charging to the closed circuit 8C of the hydraulic mission is stopped during the relief operation or the amount of supplied oil changes due to a decrease in volumetric efficiency of the pump 8A). Thus, the loss horsepower can be reduced by the charge pump.
3 and 6 to 8, details of the hydraulic device 10 having the direction control valve 43 and the hydraulic pressure take-out port 40A, the reinforcing frame 12, and the like are shown.
The hydraulic oil from the third pump 37 dedicated to the swing (priority) is sent to the direction control valve 43 for the control valve 29 for controlling the left and right swing cylinders 23 via a delivery pipe (swing circuit) 37A. The valve 43 is mounted as shown in FIG. 8 on the right side front portion of the casing in the hydraulic apparatus 10 having the left and right lift arms 10A.
[0022]
As shown in FIG. 8, the hydraulic pressure switching block 43B of the directional control valve 43 includes a switching spool 43D and a relief valve 43E for switching the hydraulic pressure by the operating tool 43C, and a pair of connection ports 43F and 43G having couplers 43A and 43A. One is for the inlet port (import connection port) and the other is for the tank port (out port connection port). When working with the backhoe B attached to the tractor T, the swing circuit (delivery pipe) 37A is used. The oil from the dedicated pump 37 is sent to the direction control valve 43 through the oil, and the oil from the direction control valve 43 is sent to the swing valve 29 through the coupler 43A and the connection ports 43F, 43G. The boom 20 swings in the horizontal direction around the swing axis by swinging each of the Single operation because the supply amount of oil into cylinder 23 is constant, it is the same operability in a simultaneous operation can be obtained.
[0023]
On the other hand, when the backhoe B is detached from the tractor T, the switching spool 43D is switched so as to have an unloading function by the operation tool 43C, whereby a service port different from the main circuit is connected via the coupler 43A and the connection ports 43F and 43G. It can be.
That is, by operating the operating tool 43C and switching the spool 43D to have an unloading function as shown in FIG. 8, the relief valve 43E can set a system relief pressure different from the main circuit, and the connection ports 43F, 43G When the backhoe B is removed by configuring the service port according to the above, it can be used for a wide range of applications as a hydraulic supply source (service port) for other hydraulic equipment. At this time, the relief valve 43E can be replaced by a cartridge system or the like, for example. By doing so, a wider range of applications can be accommodated.
[0024]
The return oil from the switching block (direction control valve) 43 is returned to the tank (tractor vehicle body) T through the pipe 43H.
5 to 8, the switching valve means (direction control valve) 43 having a service port capable of setting a system relief pressure different from that of the main circuit is mounted on the right side of the hydraulic device 10 mounted on the tractor vehicle body 5. However, a hydraulic pressure switching means 60 is mounted on the left side of the hydraulic device 10.
That is, an oil passage switching block (hydraulic switching means) 60 is provided on the hydraulic delivery side (supply side) of the hydraulic device 10 and the backhoe B.
[0025]
This switching means 60 is configured such that the supply piping 39A of the directional control valve 39 shown in FIG. 3 is connected to the backhoe B side and the hydraulic device 10 side by the switching spool 60A on the upstream side of the control valve (position control valve) 10B in the hydraulic device 10. The hydraulic pressure can be switched freely.
That is, as shown in FIGS. 5 to 7, a switching block 60B is detachably mounted on the left side front surface portion of the hydraulic housing 10C constituting the hydraulic device 10, and a hydraulic outlet 40A is provided in the block 60B. The switching spool can be switched between when the hydraulic pressure from the main pump 36 is supplied to the control valve 28 of the backhoe B via the coupler 40B and when the hydraulic pressure from the pump 36 is supplied to the control valve 10B of the hydraulic equipment 10. The switching spool 60A can be switched by an operating tool 60D having a knob 60C extending rearward on the left side surface of the hydraulic housing 10C.
[0026]
The switching spool 60A is supported by the block 60B so as to be rotatable about a horizontal axis, and the tip (front end) of a rod-like operation tool 60D is pivoted by a pin or the like on an arm 60E provided at the end of the spool 60A. The hydraulic pressure from the pipe 39A can be switched between the control valve 10B side of the hydraulic device 10 and the control valve 28 side of the backhoe B. The position A1 of the solid line knob 60C in FIG. On the other hand, the position A2 removes the backhoe B, and the hydraulic device 10 allows a working machine other than the backhoe to be moved up and down via a three-point link or the like. 3P use is shown respectively.
[0027]
That is, conventionally, the hydraulic pressure switching means 60 is provided in the return oil path from the backhoe to the tractor, and this is a hydraulic circuit that 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, so that the backhoe B is separated rearward from the tractor vehicle body 5 so as not to interfere with the vertical movement of the arm 10A (front-rear spacing). In this case, the weight balance of the TLB becomes poor and the stability during running is lacking, or the total length of the TLB becomes long and cannot be transported by, for example, a 10,000 pound trailer. It was.
[0028]
On the other hand, according to the hydraulic pressure switching means 60 described above, when the backhoe B is mounted, a hydraulic circuit is provided so that the hydraulic device 10 does not move, and therefore the backhoe B can be mounted close to the tractor vehicle body 5. Thus, the problem of the switching means of the conventional example is solved.
Although the embodiment of the present invention is as described above, the hydraulic switching means 43 and 60 can be freely designed, for example, mounted in the opposite direction, 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 for swing (priority)) 37 is 27.7 l / min. It is also possible to set.
[0029]
【The invention's effect】
As described above in detail, according to the present invention, the amount of oil supplied to the cylinder that swings the backhoe boom in the left-right direction is constant, and the simultaneous operation (combined operation) such as the boom swing single operation and the boom lifting / lowering is performed. ), The same operability can be obtained, and the driver's feeling of fatigue is also reduced.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a hydraulic circuit in 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 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 hydraulic piping.
FIG. 6 is a rear view of the TLB.
FIG. 7 is a side view showing hydraulic pressure switching means between the backhoe and the hydraulic device.
FIG. 8 is a plan view showing switching means between backhoe hydraulic pressure and service port hydraulic pressure.
[Explanation of symbols]
T tractor B backhoe L front loader 1 TLB
20 Boom 23 Swing cylinder 29 Swing control valve 37 Swing pump

Claims (2)

A left and right swing cylinder (23) that swings the boom (20) of the backhoe (B) attached to the tractor (T) in the left-right direction, and a control valve (29) that controls the swing cylinder (23); An independent swing circuit (37A) for supplying and discharging hydraulic oil from a dedicated pump (37) to and from the control valve (29) ;
Between the dedicated pump (37) and the control valve (29) of the swing circuit (37A)
A directional control valve (43) is provided, and the directional control valve (43) is a switching spool (43D) for switching the operation oil from the dedicated pump (37) between the control valve (29) side and the drain side. And a relief valve (43E) for draining hydraulic oil from the dedicated pump (37) when the hydraulic pressure of the swing circuit (37A) rises,
The dedicated pump (37) and the direction control valve (43) are provided on the tractor (T) side, the left and right swing cylinders (23) and the control valve (29) are provided on the backhoe (B) side, and a swing circuit ( 37A) A hydraulic system for a tractor-mounted backhoe, wherein a detachable coupler (43A) is interposed between the directional control valve (43) and the control valve (29) .   Control each of the boom cylinder (24), the pair of stabilizer cylinders (27), the arm cylinder (25) and the bucket cylinder (26) on the downstream side of the control valve (29) for controlling the left and right swing cylinders (23). The tractor-mounted backhoe hydraulic system according to claim 1, wherein the control valves (30), (31), (32), (33), and (34) are connected in parallel.

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