JPH0138441B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic system attached to the lateral outer side of a transmission case that is equipped with a control valve for raising and lowering a lift arm, and in particular, the present invention relates to a hydraulic system that controls a constant amount of oil for controlling the posture of an attached working device. This invention relates to improvements when using a flow priority valve to ensure flow priority.

Conventionally, the flow priority valve used for the above purpose has a pump port, a tank port, and a supply port for the lift arm drive circuit that are opened on the side of the transmission case on the mounting surface of the transmission case of the casing. In addition to forming an input port, a tank port, and a lift arm pressure oil takeout port that communicate with each other, a control flow takeout port and a return port are provided on the outer surface of the casing, and the return oil of the control flow and surplus flow are carried out within the casing. It was configured to merge and send out to the lift arm pressure oil extraction port on the mounting seat surface.

For this reason, if it becomes necessary to drive a hydraulic actuator for changing the posture of the work equipment, another control valve block or pressure oil extraction block is required on the lateral outer surface of the flow priority valve. The structure is such that the blocks are connected in series in order to take out the pressure oil as appropriate.The more connected blocks there are, the more problems occur due to oil leakage at the connecting surfaces, and if sufficient sealing is performed, the connecting structure becomes complicated. Along with this, the time required for assembly also increased. In addition, in the conventional type, it was not possible to attach a solenoid control valve directly to the flow priority valve, so in order to perform electric control, the solenoid control valve was connected through external piping, and the assembly was difficult. It took a considerable amount of time to attach.

The present invention has been made in view of these circumstances, and by modifying the casing of the flow priority valve, it is possible to lubricate multiple control valves, especially electromagnetic control valves, without using a take-out block. To provide a hydraulic device that can be easily assembled without fear of leakage and allows easy configuration of a hydraulic circuit for controlling the posture of a working device according to various types of agricultural work.

Embodiments of the present invention will be described below based on the drawings.

1 and 2, the rear end of the main tractor 1 is equipped with a pair of left and right lift arms 3, 3 that are driven by a single-acting hydraulic cylinder 2 and swing up and down in a pair. , a three-point link mechanism 6 consisting of a top link 4 and left and right lower links 5, 5 is attached, and the left and right lift arms 3, 3 and left and right lower links 5, 5 are connected to lift rods 7, 8, respectively.
are connected with. And each lower link 5,
A box-type ground leveling scraper 9 is connected across the rear end of the top link 5 and the rear end of the top link 4.
The lift rod 7 on the left side is configured as a double-acting hydraulic cylinder, the lift rod 8 on the left side is configured to be extendable and retractable using a turnbuckle system, and the top link 4 is also configured as a double-acting hydraulic cylinder. has been done.

In this way, the lift arm cylinder 2 drives the entire ground leveling scraper 9 up and down, and the expansion and contraction of the lift rod cylinder 7 causes the scraper 9 to roll from side to side, and the expansion and contraction of the top link cylinder 4 causes the scraper 9 to move horizontally. The scraper 9 is configured to change its forward and backward inclined posture.

In the ground scraper 9, a stay 12 having brackets 11, 11 for connection with lower links 5, 5 is horizontally fixed to the front part of a horizontally long box-shaped frame 10, and a top link cylinder 4 and a top link cylinder 4 are connected to each other from this stay 12. A connecting mast 13 is erected, and a frame 15 made of a square pipe in which a large number of cutting teeth 14 are arranged side by side is hung horizontally within the box-shaped frame 10, and a fixed blade is attached to the lower edge of the rear end of the box-shaped frame 10. 16 and a reversing blade 17 that can swing rearward and upward, and by driving and rotating the cutting tooth mounting frame 15 by a hydraulic cylinder 18, the cutting teeth 14 are attached to the box-shaped frame. 1
0 can be operated in and out from the bottom of the front end.

Next, the hydraulic pressure control circuit configuration of the hydraulic cylinders 2, 4, 7, and 18 will be explained with reference to FIG.

In the figure, 20 is a first flow priority valve that receives pressurized oil from a pump 21 driven by an engine mounted on the tractor.
A certain amount _Q1 of the supplied flow rate Q is sent as a control flow to the hydraulic control circuit of a hydraulic clutch type forward/reverse switching mechanism (not shown), and the remaining flow rate _Q2 is sent as a surplus amount to the second flow priority valve 22. Supplied. The control flow q ₁ of this second flow priority valve 22 is supplied in series to an electromagnetic control valve 23 that controls the operation of the lift rod cylinder 7 and an electromagnetic control valve 24 that controls the operation of the top link cylinder 4. The return oil from these electromagnetic control valves 23 and 24 is combined with the surplus flow q ₂ of the second flow priority valve 22 via the check valve 25, and this combined pressure oil, that is, from the first flow priority valve 20 is The entire surplus amount _Q2 is supplied to the electromagnetic control valve 26 of the hydraulic cylinder 18 for advancing and retracting the cutting teeth, and further, through this valve 26, pressure oil is supplied to the position control valve 27 of the lift arm cylinder 2. It's summery.

The position control valve 27 is connected to the position control lever 2 via a spool operating lever 28.
It consists of a main spool 30, a poppet valve 31 and an unload valve 32, which are connected to the main spool 9.
Then, in response to the swinging operation of the control lever 29, the main spool 30 and the poppet valve 31 are
is shifted and the lift arm 3 is raised and lowered, and the displacement of this lift arm 3 is caused by the feedback link 3.
3 to the spool operating lever 28, the lift arm 3 is configured to automatically stop when it moves up and down to a predetermined position corresponding to the operating position of the control lever 29.
Electromagnetic control valve 23 of the lift rod cylinder 7
Not only can the roller cylinder of the sprayer 9 be adjusted arbitrarily by operating the hand switch in the driving section, but it can also be automatically operated based on the detection result of the left and right tilt detection sensor 50 attached to the scraper 9. It is constructed so that it can always be kept in a horizontal position on both sides. Incidentally, since this automatic rolling control mechanism is the same as the known one, a detailed explanation thereof will be omitted. Further, the electromagnetic control valve 24 of the top link cylinder 4 and the electromagnetic control valve 26 of the cutting tooth extension/retraction hydraulic cylinder 18 are each switched by operating a hand switch.

Next, a specific mounting structure of the control valve group will be explained.

Mission case 40 in tractor main machine 1
An upper cover case 41 housing the lift arm cylinder 2 is connected to the rear upper surface of the holder, and the position control valve 27 is connected to the inner surface of the upper cover case 41.
is installed. Further, the first flow priority valve 20 is connected to the left side surface of the upper lid case 41 via a spacer 42, and this side outer surface
_S1 , the second flow priority valve 2
2. A rectangular valve block 45 incorporating a main relief valve 43, a branch relief valve 44, and a check valve 25 is connected. When the surplus oil extraction port a, the tank port b, and the supply port c for pressure oil for driving the lift arm are opened on the lateral outer surface of the casing of the first flow priority valve 20, they are connected to the mounting seat surface of the valve block 45. An input port a', a tank port b', and a pressure oil outlet port c' corresponding to the ports a, b, and c are opened.

The upper surface _S2 of the valve block 45 is finished flat as a whole in order to serve as a valve mounting seat surface, and an electromagnetic control valve 26 for advancing and retracting cutting teeth is directly connected to the right end of the upper surface S2. A valve plate 46 with an internal oil passage is placed across the center and left end of _S2 , and an electromagnetic control valve 23 for the lift rod cylinder and an electromagnetic control valve 24 for the top link cylinder are arranged side by side on the upper surface _S3 . The control valves 23 and 24 and the valve plate 46 are fastened together to the valve block 45 by connecting bolts 47.

Further, on the upper surface _S2 of the valve block 45, a port d for taking out the control flow _q1 of the second flow priority valve 22 and its return port c, a first takeout port f for the combined oil and its return port g, and a Two take-out ports h and their return ports i are opened, respectively, and three sets of ports j, k, and
l, m, and n, o are open.

Further, on the rear surface _S4 of the valve block 45, three sets of connection ports j', k', l', m', and n', o' communicating with the three sets of ports j, k, etc. are opened, respectively. is,
These are pipe-connected to each cylinder 7, 4, 18.

In the embodiment, two sets of combined oil take-out ports and return ports are provided on the top surface of the valve block 45.
g, h-i are provided, but it is also possible to provide a larger number of sets. If there is a port pair that is not used, a communication block may be separately provided to allow communication between the ports. Further, the combined oil outlet and return ports fg and hi may be provided on a different surface from the open side of the control flow outlet and return ports de. Further, when the first flow priority valve 20 is not used, the valve block 45 is connected to a spacer 42 having ports corresponding to the ports a, b, and c.

As described in detail in the embodiments above, the present invention provides a valve block 4 on the lateral outer side of the transmission case 40 in which the control valve 27 for driving the lift arm 3 up and down is installed.
5, and connect the pressure oil input port to the mounting surface of this valve block 45 on the transmission case side.
a', tank port b', and lift arm drive pressure oil extraction port c' are opened, respectively, and connected and communicated with predetermined ports a, b, and c on the transmission case side,
A flow priority valve 22, a main relief valve 43, and a branch relief valve 44 are incorporated into the valve block 45, and a port d for taking out the control flow _q1 from the flow priority valve 22 and its return port e are connected to the outer surface of the valve block. A check valve 25 is installed internally, which opens in a flat surface for mounting a valve provided in the valve, and allows the return control flow q ₁ flowing from the return port e to unilaterally join the surplus flow q ₂ from the flow priority valve 22 . , take-out ports f and g for taking out and returning the combined oil are opened in a flat surface for mounting a valve formed on the outer surface of the valve block,
Further, since the most liquid confluence oil return port i is internally communicated with the lift arm drive pressure oil take-out port c', the following effects are achieved.

In other words, the valve block 45 is provided with not only a pair of control flow take-out and return ports, but also multiple sets of ports f-g, h-i that take out and return the combined oil of the return control flow and excess flow in series. Therefore, unlike the conventional structure in which various valves and hydraulic extraction blocks are sequentially connected in series on the side of the flow priority valve, the weight of the valves and blocks acts on the directly connected parts, causing oil leakage. It is now possible to easily construct a desired hydraulic circuit by selectively and independently assembling the necessary control valves at appropriate locations on the valve block.

In addition, each oil outlet and return port is opened on the flat valve mounting surface so that a solenoid control valve can be directly mounted, allowing various automatic controls for adjusting the posture of work equipment using electric circuits and hand switch operation. It has become possible to easily configure the hydraulic circuit that performs this with fewer external piping.

[Brief explanation of drawings]

The drawings illustrate an embodiment of the hydraulic system for an agricultural tractor according to the present invention, in which Fig. 1 is an overall side view with a soil leveling scraper connected, Fig. 2 is a perspective view of the rear part of the machine, and Fig. 3 is a hydraulic circuit. FIG. 4 is an exploded perspective view of the control valve mounting portion. 3... Lift arm, 22... Flow priority valve, 25... Check valve, 40... Mission case, 43... Main relief valve, 44...
...Diversion relief valve, 45...Valve block, a, b, c...g, h, i...Port, q ₁ ...
Control flow, q ₂ ... Surplus flow.

Claims (1)

[Claims] 1. A valve block 45 is installed on the lateral outer side of the mission case 40 that houses the control valve 27 for driving the lift arm 3 up and down, and a pressure oil input port a is installed on the mounting seat surface of the valve block 45 on the mission case side. ', tank port b' and lift arm drive pressure oil take-out report c' are opened and connected to predetermined ports a, b, and c on the mission case side, and a flow priority is installed in the valve block 45. The flow priority valve 22, the main relief valve 43, and the branch relief valve 44 are assembled, and a port d for taking out the control flow _q1 from the flow priority valve 22 and its return port e are formed on a flat surface for mounting the valve provided on the outer surface of the valve block. A check valve 25 that opens and unilaterally merges the return control flow q ₁ flowing from the return port e with the surplus flow q ₂ from the flow priority valve 22 is installed, and this combined oil is taken out and returned. The ports f and g are opened in a flat surface for mounting the valve formed on the outer surface of the valve block, and the final combined oil return port i is internally communicated with the take-out port c' of the lift arm driving pressure oil. Hydraulic system for agricultural tractors.