JPH0466005A - Hydraulic controlling apparatus of tractor - Google Patents

Abstract

PURPOSE:To preferentially secure the flow rate of a three-point link control valve even in the case of lowering the real delivery rate of a hydraulic pump and to ensure the flow of oil to the side of an auxiliary control valve by setting the flow rate of the three-point link control valve to have priority over that of the auxiliary control valve. CONSTITUTION:The objective apparatus is provided with an electromagnetic proportional three-point link control valve 8 and auxiliary control valves 9, 10 and with a correction part 25 and a preferential ratio setting part 23 to set a preferential ratio for setting the flow rate of the side of the three-point link control valve 8 to have priority over that of the auxiliary control valve 9, 10. The real delivery rate of a hydraulic pump 11 is detected by a delivery rate detection part 19. When the detected real delivery rate is lower than the total ordered flow rate, the correction part 25 reduces the ordered flow rate of the side of auxiliary control valves 9, 10 according to the preferential ratio. Individual control valves 8, 9, 10 are controlled to adjust the real delivery rate to the corrected ordered flow rate. Accordingly, a flow of the ordered rate is preferentially flowed at the side of the three-point link control valve 8 and the flow of the corrected ordered flow rate is also given to the side of the auxiliary control valves 9, 10.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic control device for a tractor.

(Prior art) In a tractor, a flow rate proportional electromagnetic proportional valve is used as a three-point link control valve and an auxiliary control valve, and a command signal is given to these control valves from a potentiometer linked to a joystick-type operating lever to operate them. There is a trend toward adoption of hydraulic control devices that proportionally control the command flow rate of each control valve using a command signal proportional to the inclination angle of the lever.

(Problem to be Solved by the Invention) When a tractor is equipped with this type of hydraulic control device and a work implement is attached to its three-point link to perform a specified harvest, if the actual discharge amount of the hydraulic pump is reduced. Even though each control valve is an electromagnetic proportional type, the flow rate on the three-point sink control well side may drop drastically or become zero. For example, when a compatible plow is attached to a three-point link and the reversing operation of the plow is performed by a hydraulic cylinder connected to an auxiliary control valve, the three-point link lifts the plow when turning at the edge of the field, and the hydraulic cylinder At this time, if the engine speed is reduced too much and the actual discharge amount of the hydraulic pump becomes less than the total required flow rate of the three-point link control valve and the auxiliary control valve,
Even though an electromagnetic proportional control valve is used, most of the oil flows to the side of the auxiliary control valve with a light load, and the flow rate of the 3-point link control valve with a heavy load decreases extremely or reaches zero. It may become. Therefore, the lifting operation of the plow becomes slow, making it impossible to perform work quickly.

In view of these points, the present invention preferentially secures the flow rate of the three-point link control valve example even when the actual discharge amount of the hydraulic pump decreases, and also ensures that oil always flows to the auxiliary control valve side. The purpose is to

(Means for Solving the Problems) The present invention includes an electromagnetic proportional three-point link control valve 8 and auxiliary control valves 9, 10, and the command flow rate of these control valves 8, 9, 10 is controlled proportionally. In the hydraulic control system for a tractor, the discharge amount detection unit 19 detects the actual discharge amount Q of the hydraulic pump 11 and the flow rate of eight three-point link control valves is given priority over the flow rate of the auxiliary control valves 9 and 10. The priority ratio setting section 23 sets the priority ratio, and when the actual discharge amount Ω of the hydraulic pump 11 is smaller than the total command flow rate of each control valve 8, 9. It is equipped with a correction section 25 that corrects the command flow rate.

(Function) The discharge amount detection section 19 detects the actual discharge amount of the hydraulic pump 11, and if the actual discharge amount becomes less than the total command flow rate, the correction section 25 sets the
A correction is made to reduce the command flow rate of the point link control valve 8 auxiliary control valves 9 and 10 according to the priority ratio. Then, each control valve 8.9, 10 is controlled so as to achieve this corrected command flow rate.

Therefore, the correction command flow rate flows preferentially to the three-point link control valve 8 side, and the correction command flow rate also flows to the auxiliary control valves 9 and 10 side.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

In Figure 1, 1 is a three-point link at the rear of the tractor body 2, 3 is a hydraulic system for lifting and lowering the three-point link, and lift arm 4 is
, the three-point link 1 is raised and lowered via a lift rod 5. Reference numerals 6 and 7 indicate first and second hydraulic cylinders on the working machine side, which are mounted on the tractor body 1. 8 is 3
Point link control valve, 9.10 is the first and second auxiliary control valve,
These control valves 8.9 and 10 are composed of flow rate proportional electromagnetic proportional valves. Reference numeral 11 denotes a load sensing type swash plate type variable displacement hydraulic pump, which is driven by an engine 12.

13 is a charge pump, 14 is a strainer, and 15 is a filter. 16 is a command unit for the three-point link control valve;
This is equipped with a position setting section, a draft setting section, a lift arm upper limit setting section, a lift switch, etc. 1
Reference numeral 7.18 denotes first and second command parts for the auxiliary control valve, each of which is provided with a flow rate upper limit setting part. These command units 16, 17, and 18 are composed of volumes, potentiometers, etc., and are designed to output steplessly changing command signals.

Reference numeral 19 denotes a discharge amount detection unit that detects the actual discharge amount Q of the hydraulic pump 11, and is configured to calculate the actual discharge amount Q from signals from the rotation sensor 2o of the hydraulic pump 11 and the swash plate angle sensor 21. 22.23 is a priority ratio setting section, and the priority ratio setting section 23 sets a priority ratio α in which the flow rate on the three-point link control valve 8 side has priority over the flow rate on the auxiliary control valve 9.10 example. A priority ratio β is set for each of the nine first auxiliary control valves to give priority to the flow rate over the second auxiliary control valve 10 side flow rate.

24 is an arithmetic control section that determines the magnitude of the actual discharge amount Q from the discharge amount detection section 19, and if it is larger than the total command flow rate of each control valve 8, 9.10, each command section 16.17. The control valves 8.9.10 are controlled proportionally in accordance with the command signals from the control valves 8.9. 10 is corrected by the correction unit 25 (see FIG. 2), and based on the corrected command flow rate, each of the control valves 8, 9.
It has the function of controlling 10. The error detection section 19', setting sections 22 and 23, and arithmetic control section 24 are constituted by a microcomputer or the like.

Next, the operation will be explained. When a working machine such as a summer plow is raised and lowered by the hydraulic device 3 or reversed by the hydraulic cylinder 6.7, the desired command unit 16.17.18
Operate as appropriate using the lever or other means. Then, a command flow signal proportional to the operation amount is sent to the control section, and the control valves 8 and 9 are
．． 10 operates proportionally in accordance with the signal, and sends a commanded flow rate of oil to the hydraulic device 3, hydraulic cylinders 6, 7, etc. At this time, the following control is performed.

Now, as shown in FIG. 2, the command flow rate of the three-point link control valve 8 is set to 312. Set the command flow rate of auxiliary control valve 9.10 to 2 II
I + X ml, and the priority ratios variably set by the priority ratio setting units 22 and 23 are α and β.

Further, the corrected command flow rate obtained by correcting the command flow rate 7:+r, 1, I-□ of each control valve 8, 9.10 according to the priority ratio is set to 3°3P + J'llll * I'&Z.

When the hydraulic pump 11 operates, the rotation sensor 20 and the swash plate angle sensor 21 operate, and the discharge amount detection unit 19 calculates the actual discharge amount Q of the hydraulic pump 11 based on the rotation speed and the swash plate angle signal. Figure step ■). And each control valve 8,
9. If 10 are activated at the same time, in step 2, the magnitude relationship between the actual discharge amount Q and the total command flow rate 3, +3□+31 is compared, and the actual discharge amount Q is determined to be the total command flow rate 1xr+1m.
If it is ++3a□ or more, each control valve 8.9.10 is operated proportionally so that each command flow rate is achieved. That is, control is performed in proportion to the command signal from the command section 14, 15, 16.

If the actual discharge amount Q is smaller than the total command flow rate 13p+l-III-z, the process moves to the next step ■, and the auxiliary control valve 9
, 10 side command flow rate 7m+, 7m□ is the priority ratio α.

Correct according to β, and the correction command flow rate 3°11, 3°,
Find 2. At this time, no correction is made on the three-point link control valve 8 side, and the commanded flow rate g3F is secured preferentially. Then, the actual discharge amount Q is the total command flow rate after correction 1sp+l°a++7'1
□ If the above is the case, the command flow rate 3 will flow preferentially to the three-point link control valve 8 side, and the actual discharge amount Q will flow to the three-point link control valve 8 side to each auxiliary control valve 9 and 10 side. flow rate 03P
The remaining flow rate after subtracting is distributed according to the priority ratio β between the two. Therefore, the flow rate of the auxiliary control valve 9.10 example is (Q
Q3F)・3°,, /3°al+J'mZ, and the auxiliary control valve 9. The flow rate on the IO side is (Q-Q3F)・l"-t
/ l'-+ + i-z.

The actual discharge amount Q is the command flow rate 2111 on the auxiliary control valve 9.10 side.
If correcting +l at is not enough,
Moving on to step (2), the command flow rate 2. of the three-point link control valve 8.
2, and the corrected command flow rate is 2゛.

Perform the same process by taking into account the following. That is, if the actual discharge amount Q is equal to or greater than the total corrected command flow rate 1''xp+l°ml+2',a;, each control valve 8, 9, 10 is operated accordingly.

In addition, if the actual discharge amount Q is small, the actual discharge amount Q is
, 9.10 correction command flow rate 2°3F+ 2'llll+
Distribute according to y'az.

In this way, even if the actual discharge amount Q of the hydraulic pump 11 changes, the three-point link control valve 8 side will always have the command flow rate 13F,
Alternatively, since a flow rate greater than that of the auxiliary control valve 9.10 can be secured by the priority ratio α, the hydraulic system 3 can reliably raise and lower the working machine.

On the other hand, when the actual discharge amount port becomes less than the total command flow rate, the three-point link control valve 8 side is switched to the auxiliary control valve 9 according to the priority ratio α. The oil only flows more than the IO side, and the oil also necessarily flows to the auxiliary control valves 9 and 10. The same goes for the auxiliary control valves 9 and 10.

FIG. 4 shows a case where a load sensing operation is performed using a fixed capacity hydraulic pump 11. Note that other controls are the same as in the case of FIG. A variable flow rate priority valve 26 is interposed between the hydraulic pump 11 and each control valve 8, 9.10, and this priority valve 26 is connected to a load sensing circuit 27 connected to each control valve 8, 9.10. It is activated by a pressure change with a sensing circuit 28 connected to the outlet side. In addition, 29.30 is a safety valve. Also 3
The point link control valve 8 is composed of an ascending proportional solenoid valve 31, a descending proportional solenoid valve 32, a forced descending solenoid valve 33, a safety valve 34, a switching valve 35, an unloading valve 36, and the like. The auxiliary control valves 9, 10 are composed of proportional solenoid valves 37, 38 and safety valves 39, 40.

In this circuit, a three-point linkage control valve 8, an auxiliary control valve 9. If IO is not used, sensing circuit 2
The priority valve 26 is switched to the unloading side by the pressure of 7,
The entire amount of oil discharged from the hydraulic pump 11 is unloaded. In addition, if any or all of the three-point link control valve 8 and the auxiliary control valve 9.10 are used, the load sensing circuit 27
senses the load, so the priority valve 26 controls the control valves 8, 9.1.
Pour the required amount of oil on the 0 side and unload the rest. Therefore, compared to the case where a load-sensing type hydraulic pump 11 is used, the efficiency is slightly inferior, but the structure is significantly simpler, so it is very advantageous in terms of cost.

In the embodiment, a summer plow was used as an example of the working machine, but when the working machine side needs to be moved while giving priority to the lifting and lowering operation of the 3-point sink (for example, a rotary cutter, etc.) ) can be widely used.

(Effects of the Invention) According to the present invention, the discharge amount detection unit 19 that detects the actual discharge amount port of the hydraulic pump 11 and the flow rate of the eight three-point link control valves are set to be higher than the flow rate of the auxiliary control valves 9 and 10. A priority ratio setting section 23 sets a priority ratio to be prioritized, and when the actual discharge amount Q of the hydraulic pump 11 is smaller than the total command flow rate of each control valve 8.9.10, the auxiliary control valve 9.10 is set according to the priority ratio. Since it is equipped with a correction section 25 that corrects the command flow rate on the side, even when the actual discharge amount of the hydraulic pump 11 decreases, the flow rate on the three-point link control valve 8 side is preferentially ensured, and the auxiliary control valve 9
, 10 side as well.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams thereof, and FIG. 4 is a hydraulic circuit diagram showing another embodiment of the present invention. 8... Three-point link control valve, 9.10... Auxiliary control valve, 11... Hydraulic pump, 16, 17.18... Command section, 19... Discharge amount detection section, 22.23 . . . Priority ratio setting section, 24 . . . Arithmetic control section, 25 . . . Correction section.

Claims (1)

[Claims] (1) Equipped with an electromagnetic proportional three-point link control valve (8) and auxiliary control valves (9) (10), these control valves (8) (9)
(10) A hydraulic control device for a tractor that proportionally controls the commanded flow rate includes a discharge amount detection section (19) that detects the actual discharge amount (Q) of the hydraulic pump (11), and a three-point link control valve ( A priority ratio setting section (23) that sets a priority ratio that gives priority to the flow rate of the 8) side over the flow rate of the auxiliary control valves (9) and (10), and the actual discharge amount (Q) of the hydraulic pump (11).
is smaller than the total command flow rate of each control valve (8) (9) (10), each control valve (8) (9) (10) according to the priority ratio.
1. A hydraulic control device for a tractor, comprising: a correction section (25) for correcting a command flow rate on the ) side.